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Online 1. Developing angular intensity correlations of Xray photons as a tool for studying structures of proteins in noncrystalline solutions [2019]
 Qiao, Shenglan, author.
 [Stanford, California] : [Stanford University], 2019.
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This dissertation offers lessons learned and tools developed as we attempt to apply correlated Xray scattering (CXS) to noncrystalline proteins in solution. It builds on our previous work of extracting correlation signals from scattering intensities of ensembles of mental nanoparticles, which has led to threedimensional (3D) structural insights not reflected in azimuthally averaged measurements. In his 1977 paper, Zvi Kam proposed the idea of correlating Xray photons scattered by an ensemble of randomly oriented particles suspended in solution. He found that if the exposure time is much shorter than the diffusion timescale of Brownian motion, correlations between photons scattered into different angles encode 3D structural information of the particles not accessible via conventional small or wideangle Xray scattering. The advent of the Xray free electron laser (XFEL) renders Kam's idea feasible for noncrystalline solutions of proteins. With femtosecond pulses and extremely high fluences, the XFEL is not only capable of probing ensembles of molecules essentially frozen in time but also delivering a large number of photons per pulse, a capability critical for enhancing angular intensity correlation signals. Meanwhile, probing proteins in solution removes the need for crystallization, allows measurements of mixtures of conformational states under physiological conditions, and broadens opportunities for timeresolved experiments. The body of work in this dissertation draws from scattering data collected with samples containing the Gprotein Gi alpha subunit during two separate beam times conducted at the Linac Coherent Light Source. The Gi alpha subunit was chosen for these proofofprinciple experiments because of its important role in the Gprotein coupled receptor signaling pathway. This dissertation has taken the first steps in developing and validating CXS as a tool for probing ensembles of biomolecules in solution. These first steps as well as ideas described in this dissertation to improve CXS towards a mature pipeline that yields reliable and detailed structural insights aim to inspire others in the solution scattering community to engage with the unique challenges and rewards of this technique.
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Online 2. From timeresolved to frequencyresolved xray scattering [2019]
 Ware, Matthew Robert, author.
 [Stanford, California] : [Stanford University], 2019.
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 Book — 1 online resource.
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Gasphase timeresolved xray scattering (TRXS) measures internuclear separations in a molecule following laserinduced photoexcitation. TRXS constitutes an indirect measurement of the molecular motion because it captures information in reciprocalspace and realtime, which then must be inverted to recover the charge density as it changes in time. The spatial resolution of the recovered charge density is fundamentally restricted by the xray wavelength used in the experiment. There is no corresponding technical restriction on the ability to scan the delay between the pumplaser pulse and the xrayprobe pulses, and thus no lower limit on the ability to resolve beat frequencies from TRXS measurements. This observation motivates transforming the measured TRXS in reciprocalspace and realtime into its reciprocalspace and reciprocaltime representation through a temporal Fourier transform. This representation is called frequencyresolved xray scattering (FRXS). The novel aspect of this approach is that an interpretable and compact representation of the experimental measurement may be obtained in reciprocalspace and reciprocaltime without the difficulty of inverting the measurement to the traditional realspace and time representation, and thus FRXS presents an alternative to traditional analyses of TRXS. The traditional approach based on pair correlation functions is limited by the range of momentum transfer, Q, that is accessible at xray free electron lasers (FELs). FRXS does not suffer this limitation, and in fact, FRXS leverages the strengths of FELs, namely fine time resolution and (relatively) fast data accumulation. This enables a long range of pumpprobe delays to be measured in an experiment, thus improving the frequency resolution of an experiment, while maintaining sufficient temporal resolution to measure high beat frequencies. These advantages have been used to obtain compact representations of bound states and dissociations along lines in reciprocalspace and reciprocaltime, demonstrating an alternative to traditional analyses of timeresolved xray scattering for gasphase photochemistry.
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 Chen, Ruizhu, author.
 [Stanford, California] : [Stanford University], 2019.
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 Book — 1 online resource.
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In this thesis, we use helioseismic methods to study two separate topics, the Sun's meridional circulation and sunquake events. The Sun's meridional circulation is a key component of solar dynamo and interior dynamics, playing an important role in transporting magnetic flux and redistributing angular momentum. A profile of the meridional circulation has long been sought, but results from previous studies were not fully consistent, due to a systematic center tolimb (CtoL) effect in helioseismic measurements that complicates the inference of meridional circulation in the deep interior. In the first part of this thesis, we measure the Sun's meridional circulation and its temporal evolution using 8 years of SDO/HMI Dopplervelocity observations, with a new CtoLeffectremoval method that we have developed in timedistance helioseismology. The longtimeaveraged meridional circulation profile is found to have a threelayer flow structure: an equatorward flow is sandwiched between two poleward flow zones above and beneath it, indicating a doublecell circulation in each hemisphere. Moreover, the 3layer flow pattern is more significant when the Sun's magnetic activity level is low, while significant changes are found in the flow structure during the active phase of the solar cycle. Besides, we also study the observational properties of the CtoL effect in the measured travel time of helioseismic waves. The CtoL effect is found isotropic relative to the azimuthal angle around the solar disk center. It also exhibits a significant frequency dependence  it reverses sign at a frequency around 5.4 mHz, and is strongest at around 4.0 mHz. The tendency of frequency dependence varies with diskcentric distance but not with the waves' travel distance. In the second part this thesis, we focus on sunquakes. Sunquakes are helioseismic power enhancements initiated by solar flares, but not all flares generate sunquakes. It is curious why some flares cause sunquakes while others do not. Here we propose a hypothesis to explain the disproportionate occurrence of sunquakes: during a flare's impulsive phase when the flare's impact acts upon the photosphere, a sunquake tends to occur if the background oscillation at the flare's footpoint happens to oscillate downward, in the same direction with the impulse from above. To verify this hypothesis, we survey 60 strong flares in Solar Cycle 24 to search for sunquakes, by reconstructing the oscillatory velocity in the flare sites using a helioseismic holography method. A total of 24 flares are found to be sunquake active, giving a total of 41 sunquakes. It is found that in 3 − 5 mHz frequency band, 25 out of 31 (81%) sun quakes show net downward oscillatory velocities during the flares' impulsive phases, and in 5 − 7 mHz frequency band, 33 out of 38 (87%) sunquakes show net downward velocities. These results support our hypothesis that a sunquake more likely occurs when a flare impacts a photospheric area that happens to have a downward background oscillation.
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Online 4. Impurity quantum phase transitions in quantum dot nanostructures [2019]
 Peeters, Lucas Bernd Marie, author.
 [Stanford, California] : [Stanford University], 2019.
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Electronic systems subject to competing interactions can end up in different phases as the balance between these interactions shifts. When a quantum critical point separates these phases, exotic electronic behavior often marks the vicinity of the transition. In this work, we construct nanopatterned devices to probe such critical phenomena. The basic element of our devices is the GaAs/AlGaAs quantum dot, an isolated region of electronic charge which is coupled to a twodimensional gas of weakly interacting electrons. We use different designs of quantum dots to realize different models. The first device studied in this work realizes the spin twochannel Kondo ('spin 2CK') model. In this model, a single impurity (i.e. a single spindegenerate dot) is coupled to two separate reservoirs. When the couplings to both reservoirs are unequal, the more strongly coupled reservoir screens the impurity spin degeneracy and forms a manybody singlet; this is known as the Kondo effect. When both reservoirs are coupled equally strongly, a nonFermi liquid ground state arises as a result of the overscreening by both reservoirs. We probe the anomalous scaling properties of this state, and show how it transitions into a more conventional Fermi liquid under the influence of various perturbations. The second device is first operated as a single metallic quantum dot in the quantum Hall regime. Spin degeneracy is broken, but the device can be tuned such that there is now a charge degeneracy which can then be screened by coupling to a reservoir. We tune to and away from equal couplings to see the effect of the twochannel Kondo state. Finally, we operate the second device in its full form as a doubledot device, to explore the competition between dotlead and interdot interactions.
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Online 5. The LZ dark matter search and development of a new gas phase technique to characterize low level electron emission from electrode grids [2019]
 Ji, Wei, 1990 author.
 [Stanford, California] : [Stanford University], 2019.
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Dark Matter is needed to explain many cosmological observations and therefore has been proposed for many decades, but it awaits direct detection. One of the most popular classes of dark matter candidates is Weakly Interacting Massive Particles (WIMPs), which have masses in the order of 100 GeV and couple to ordinary matter at weak scale. In WIMP direct detection experiments, we look for WIMPs being scattered by nuclei, a process which produces low energy (smaller than 100 keV) recoiling nuclei that can be observed. We are building LZ, a detector looking for WIMPs using liquid xenon in a dualphase time projection chamber (TPC), at 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. LZ aims to achieve the world's highest sensitivity to find WIMPs via WIMPnucleon interactions. After a brief discussion of dark matter and the LZ experiment, this dissertation presents the details of my study to solve the electron emission problem. The LZ TPC will consist of electrode grids and other metallic surfaces that can emit electrons when operated under voltage. Because the charge measurement in the LZ detector is sensitive to single electrons, electrons from the grids can be both a significant nuisance for data collection and a source of background at lowenergies, limiting the sensitivity of the experiment for lowmass WIMPs. This has motivated us to develop a test detector to study how to reduce this background. The test detector consists of a pair of grids biased to high voltage and operated in xenon gas. The electric field between the grid causes the electrons to produce electroluminescence scintillation light that is measured by PMTs. This new technique is sensitive to single electrons emitted by the grids, allowing a measurement of emission currents as low as attoamperes. We used this detector to study the properties of different grids and to determine what treatments can be done to reduce their electron emission. We found that passivation with citric acid reduces electron emission from stainless steel surfaces. This work was supervised by Professor Thomas Shutt and was completed in collaboration with members of the LZ collaboration and the SLAC LZ group.
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Online 6. Measurement and control of nonadiabatic dynamics a study in the acetylene dication [2019]
 LiekhusSchmaltz, Chelsea Elizabeth, author.
 [Stanford, California] : [Stanford University], 2019.
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Nonadiabatic structural dynamics occur in lighter molecules and are often described using Conical Intersections (CI) in molecules with at least three atoms. Light that is resonant near regions of strong nonadiabatic coupling can play an important role in controlling and understanding these dynamics. This thesis presents both simple model simulations and experimental data in the acetylene dication to analyze how light interacts with nonadiabatic dynamics. A key parameter that relates how the nuclear energy changes in time compared to the relative electronic energy is used to explain and predict the role that dipole coupling has in controlling nonadiabatic dynamics.
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Online 7. Measurements with optically levitated microspheres [2019]
 Rider, Alexander David, author.
 [Stanford, California] : [Stanford University], 2019.
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I discuss the development of optically levitated microspheres as a tool for precision measurements and tests of fundamental physics. Micronscale dielectric spheres are trapped by the radiation pressure at the focus of a Gaussian laser beam, where the optical suspension enables thermal, electrical, and mechanical isolation from the surrounding environment at high vacuum. Forces and torques can be measured from changes in the angle and polarization of light both transmitted through and reflected by the trapped particle. Additionally, the charge of the particle can be controlled with single electron precision. We have used these methods for the following three purposes: to search for fractionally charged particles and dark energy, to develop measurement techniques for surface potentials, and to construct an electrically driven microgyroscope.
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Online 8. Search of the Higgs boson produced through vector boson fusion decaying to a pair of bb with the ATLAS detector [2019]
 Jiang, Zihao, author.
 [Stanford, California] : [Stanford University], 2019.
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This thesis presents the search of the Higgs boson produced by Vector Boson Fusion (VBF) and decaying to bottom quarks. A search using the ATLAS detector was performed with 2016 protonproton collision data. The multivariate analysis measured the signal strengths of both the inclusive Higgs production and the vectorboson fusion production relative to the Standard Model prediction. This analysis led to the observation of Higgs coupling to bquarks in the summer of 2018. Furthermore, potential improvements of the analysis techniques using complex neural networks are investigated. In order to understand better the Quantum Chromodynamics (QCD) backgrounds of the Higgs search, the characteristic variables of the gluon splitting vertex are measured.
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Online 9. Angular momentum conservation law in lightfront quantum field theory and extended conformal symmetry of Abelian gauge theory in D ≠ 4 [2018]
 Chiu, YuJu, author.
 [Stanford, California] : [Stanford University], 2018.
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This thesis investigates two independent aspects of spacetime symmetries. The first part of my thesis is about the angular momentum conservation law in lightfront quantum field theory. We prove the lightfront Poincare invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems. We show that the lightfront wavefunction (LFWF), which describes the internal structure of a bound state, is in fact frame independent, in contrast to instant form wavefunctions. In particular, we demonstrate that j3, the intrinsic angular momentum projected onto the lightfront direction, is independent of the bound state's 4momentum and the observer's Lorentz frame. The frame independence of j3 is a feature unique to the front form. The angular momentum conservation law leads directly to a nonperturbative proof of the constraint A(0)=1 and the vanishing of the anomalous gravitomagetic moment B(0)=0. Based on the conservation of angular momentum, we derive a selection rule for orbital angular momentum which can be used to eliminate certain interaction vertices in QED and QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory. The second part of my thesis investigates an extended conformal symmetry for Abelian gauge theory in general dimensions. Maxwell theory in d \neq 4 spacetime dimensions is an example of a scaleinvariant theory which does not possess conformal symmetry  the special conformal transformation (SCT) explicitly breaks the gauge invariance of the theory. We construct a nonlocal gaugeinvariant extension of the SCT, which is compatible with the BRST formalism and defines a new symmetry of the physical Hilbert space of the Maxwell theory for any dimension d \geqslant 3. We prove the invariance of Maxwell theory in d \geqslant 3 by explicitly showing that the gaugeinvariant twopoint correlation functions, the action, and the classical equation of motion are unchanged under such a transformation.
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3781 2018 C  Unavailable In process 
 Benjamin, Nathan, author.
 [Stanford, California] : [Stanford University], 2018.
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In this thesis, we study aspects of threedimensional gravity in Anti de Sitter (AdS) space by studying the holographically dual twodimensional conformal field theory (CFT). We begin by describing general constraints on the elliptic genus of a twodimensional supersymmetric conformal field theory which has a gravity dual with large radius in Planck units. We discuss the distinction between theories with supergravity duals and those whose duals have strings at the scale set by the AdS curvature, using symmetric orbifolds as a case study. We then move on to study extremal theories, conjectured to be dual to "pure" threedimensional gravity. We first provide an example of an extremal chiral N=2 superconformal field theory at c=24. We then consider extremal CFTs at large central charge, and consider the quantum corrections to the classical spectrum. Our conjecture passes various consistency checks, especially when generalized to include theories with supersymmetry. Finally, we examine a specific topdown construction of AdS3/CFT2 from string theory, called the D1/D5 system. We examine the lowlying quarter BPS spectrum of the K3 symmetric orbifold CFT at various points in moduli space, and look at a more refined count than the ordinary elliptic genus. We do a decomposition of the spectra into N=4 characters, and show that at large N the character decomposition satisfies an unusual property, in which the degeneracy only depends on a certain linear combination of left and rightmoving quantum numbers, suggesting deeper symmetry structure.
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Online 11. Complexity and black hole geometry [2018]
 Zhao, Ying, author.
 [Stanford, California] : [Stanford University], 2018.
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This thesis discusses various aspects of black hole interior. We explore the connection between black hole geometry and quantum complexity. We look for quantum circuit protocols corresponding to traversable wormhole. We also point out various puzzles we encountered.
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Online 12. Exploring dark matter with improved numerical techniques [2018]
 Powell, Devon, author.
 [Stanford, California] : [Stanford University], 2018.
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In this thesis, I discuss several computational physics developments. The context is the study of potential dark matter observables calculated from traditional cosmological Nbody simulations. These particlebased simulation techniques often suffer from shot noise when sampling of the density field. Building on the phase space sheet (PSS) interpretation of Abel, Hahn and Kaehler (2012) of cold collisionless fluid, I develop a method for geometrically exact and robust volume and pointsampling algorithms. These operate on a simplicial tessellation of a 3manifold embedded in the 6D phase space, such that the mass is interpolated between particles, which are interpreted as Langrangian flow tracers. This results in a smooth continuous and noise free density field that aids accurate interpretations of cosmological dark matter simulations. I discuss the application of these algorithmic developments to the indirect detection of dark matter (via decay and annihilation), studies of cosmic voids, the cosmic neutrino background, and simulations. I also present recent work on extending these concepts to radiation transport with "adaptive beam tracing." This method extends raytracing, which follows 1dimensional rays along their trajectories, to beam tracing, which instead volumesamples 3D photon packets called "beams".
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Online 13. Highenergy gammaray observations of solar flares with the Fermi large area telescope [2018]
 Allafort, Alice Julia, author.
 [Stanford, California] : [Stanford University], 2018.
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Solar flares are the most energetic events in our Solar System. They consist of sudden energy release from reconfiguration of magnetic fields, leading to acceleration of particles to relativistic energies. The Fermi Large Area Telescope (LAT) gammaray observations of the Sun present a unique opportunity to explore the mechanisms of highenergy emission as well as particle acceleration and transport in solar flares. I will present the results of the first 9 years of observations of the active Sun by the FermiLAT, which represents the largest sample to date of detected solar flares with emission greater than 30 MeV. Some of the new detections confirm the standard models for solar flares based on observations from past missions in the 1980s and 90s, but new behaviors have also been identified: detections of delayed gammaray emission lasting up to 20 hours and the first detection of gammaray emission above 100 MeV from three solar flares originating from behind the visible part of the Sun. Considering all of the 46 flares detected by the FermiLAT, I will describe the characteristics of the first gammaray solar flare catalog covering Solar Cycle 24, exploring trends and correlations with the most relevant solar events: Xray emission, coronal mass ejections, and direct detection of solar energetic particles.
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Online 14. Improved discrimination for neutrinoless double beta decay searches with EXO200 and nEXO [electronic resource] [2018]
 Fudenberg, Daniel.
 2018.
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 Book — 1 online resource.
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Neutrinos have been shown to have nonzero mass, however how they generate their minuscule masses is an open question. One well motivated possibility is that neutrinos have Majorana masses, for which the most sensitive test is the observation of neutrinoless doublebeta decay. The halflife of this neutrinoless mode is much slower than that of the observed twoneutrino mode of doublebeta decay, which is many orders longer than the age of the universe, thus searches are heavily background dominated. In this work discusses two, completely distinct, methods to improve discrimination of neutrinoless doublebeta decay, of xenon136, from backgrounds. The first method is through training new discriminators to more fully exploit the observed topological information in EXO200 to distinguish neutrinoless doublebeta decay from the most common backgrounds. The second method is to enable the observation of barium136 resulting from doublebeta decay for a future generation detector via a hardwarecentric approach. One path requires extraction from high pressure gas to vacuum of heavy ions from similarly heavy medium with high efficiency. Work on a prototype extraction apparatus for the nEXO collaboration and lessons learned are presented here.
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Online 15. Improving dark energy measurements by controlling systematics in the point spread function and redshift distribution [2018]
 Davis, Christopher Paul, author.
 [Stanford, California] : [Stanford University], 2018.
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 Book — 1 online resource.
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Most of the universe is made up of dark energy, but we are unsure of its fundamental nature. Large, widefield optical galaxy surveys such as the Dark Energy Survey (DES) seek to measure any time variation in dark energy through its impact on the growth of large scale structure. Among the many features that must be controlled in order to achieve this measurement are the point spread function (PSF) and redshift distribution. In the first half of my thesis I will present a physically motivated model for the optical and atmospheric portions of the PSF and apply them to DES data. In the second half of my thesis I will turn to the measurement and calibration of redshift distributions. First, I present `clustering redshifts, ' a novel method of calibrating the redshift distributions of an ensemble of galaxies using their correlations with quasispectroscopic tracers of large scale structure, such as galaxy clusters. Then, I present a calibration of the DES Year 1 source redshift distributions using these clustering redshifts. Finally, I present a scheme for calibrating redshift distributions using selforganizing maps and overlapping infrared data. Both threads of this thesis will be useful for future cosmological galaxy surveys like the Large Synoptic Survey Telescope, Euclid, and the Wide Field Infrared Survey Telescope.
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 Kurinsky, Noah, author.
 [Stanford, California] : [Stanford University], 2018.
 Description
 Book — 1 online resource.
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The SuperCDMS SNOLAB experiment will be a 20kg scale Si and Ge direct dark matter detection experiment designed to probe down to 300 MeV in dark matter (DM) mass through DMnucleus scattering and 500 keV in DM electron scattering. In order to reach these low masses with appreciable sensitivity to dark matter, it needs to achieve very low energy resolution (≤ 10 ev) for nuclear recoils in both detector materials, which will be achieved using a new detector design and operating mode, CDMS HV. This detector is designed to operate at a bias of 100V to convert charges liberated in our detector targets to into phonon energy in order to resolve individual electronhole pairs. This has never before been achieved in a kgscale detector. In this thesis, I cover three elements of the design of the CDMS HV detectors. I discuss the detector physics controlling how charges and phonons are generated in our detector crystals, com paring theory to results of recent experiments carried out at Stanford. I move on to describe the operating principles of our phononmediated charge readout, as well as the design of the CDMS HV detector. I then describe the performance tests of early CDMS HV prototypes in conjunction with the SuperCDMS SNOLAB electronics, and discuss the path towards achieving single electronhole pair resolving detectors at the kgscale given the performance obtained thus far. As a result of these tests, we were able to refine our noise and sensor dynamics models, and develop new metrics for diagnosing nonideal sources of noise to aid in reducing coupling of the external environment to our detectors. In order to study the microphysics of phonon and charge production in our target crystals, we fabricated a number of gramscale devices with various sensor designs in order to separate sensor and environmental effects from intrinsic crystal properties. These devices provided the first successful demonstrating of using voltage to amplify charge energy by production of phonons (the NeganovTrofimovLuke effect) in order to resolve electronhole pairs, and opened up a new regime of dark matter and photon science at the gramscale that we are just beginning to explore. A first dark matter search was carried out with one of these gramscale devices, producing worldleading limits on electronrecoiling dark matter between 0.5 and 5 MeV in dark matter mass for multiple form factors. This device achieved a phonon resolution of 10 eV, allowing a single gramday of exposure to rival kgdays of exposure in the competing liquidnoble based electronrecoil search.
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Online 17. Novel methods and applications for kinetic plasma simulation [2018]
 Totorica, Samuel Richard, author.
 [Stanford, California] : [Stanford University], 2018.
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Understanding the behavior of plasma is important for a broad range of applications, such as understanding the production of energetic particles in astrophysics, developing predictive models for space weather, and harnessing the potential of nuclear fusion power. Due to limitations such as noise from numerical collisions and the large number of simulation particles required to capture the development of nonthermal tails in the particle distribution, multiscale plasma simulations are extremely challenging. In this thesis the simplexincell algorithm is presented, which holds promise for overcoming these difficulties by interpreting the simulation particles as the vertices of a mesh that traces the evolution of the distribution function in phase space. This enables a discretization using deformable phase space volume elements rather than fixedshape clouds of charge. Using test problems including Landau damping and the Weibel instability it is shown how this new view retains finescale structure in the distribution function and can drastically reduce the number of simulation particles required to reach a given noise level. Magnetic reconnection is a promising candidate mechanism for accelerating the nonthermal particles associated with explosive phenomena in astrophysics. Laboratory experiments with highpower lasers can play an important role in the study of the detailed microphysics of reconnection and the dominant particle acceleration mechanisms. In this thesis the results of particleincell simulations used to explore particle acceleration in conditions relevant for current and future laserdriven reconnection experiments are presented. These simulations indicate that laserdriven plasmas offer a promising platform for studying particle acceleration from reconnection, with the potential to reach multiplasmoid regimes of strong astrophysical interest. These results provide new insight into the physics of reconnection and particle acceleration and are now helping to guide experimental campaigns.
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 Yang, Qi, author.
 [Stanford, California] : [Stanford University], 2018.
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 Book — 1 online resource.
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To investigate the effects due to proximity between a threedimensional topological insulator (TI) and an insulating ferromagnet (IF), TIIF thin film bilayers were fabricated with pulsed laser deposition. Either bismuth(III) selenide (Bi2Se3) or bismuthantimony(III) telluride (BST) was used for the TI layer, whereas the IF layer was formed by the Heisenberg ferromagnet EuS. While a positive magnetoresistance was observed above the Curie temperature of EuS, as ubiquitously observed in highquality TI thin films, an unusual negative magnetoresistance was observed below the Curie temperature in the variablerange hopping regime. The angular dependence of such negative magnetoresistance indicates an orbit origin. Specific to BSTEuS bilayers, when the bulk conduction is minimized, magnetic anomalies in AC susceptibility were observed concurrently with resistive anomalies at the same temperatures, suggesting an interface magnetic order. These phenomena together suggest twostage proximity effects between the topological insulators and the insulating ferromagnet, and provide first steps to realize the halfinteger quantum anomalous Hall effect.
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Online 19. Quantum error correction and spacetime [2018]
 Salton, Grant, author.
 [Stanford, California] : [Stanford University], 2018.
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Quantum error correction (QEC) is a branch of quantum information theory, originally invented to protect hypothetical quantum computers against realistic sources of noise. QEC has enjoyed significant success within the paradigm of computation, but the ideas and techniques of quantum error correction have also been effective in tools many fields of physics. In this thesis, we will shed light on the way in which QEC manifests outside of the usual computational paradigm and informs other areas of physics. We'll focus on the role of QEC in quantum gravity, spacetime, and high energy theoretical physics. We start with the general problem of quantum information replication in spacetime, and we show that information replication is possible if and only if transmission of the quantum information does not result in cloning of quantum information or fasterthanlight communication. We then study the role of quantum error correction in quantum gravity, specifically within a gaugegravity duality known as AdS/CFT. We establish a new formula for mapping observables on either side of the duality, showing that the socalled bulktoboundary map defines an approximate quantum error correcting code. Motivated by the study of entangled states dual to multiboundary wormholes in AdS/CFT, we then turn our attention to characterizing the states that can arise from the euclidean path integral in threedimensional ChernSimons theories. We study U(1) level k and SO(3) level k ChernSimons theories on euclidean 3manifolds with torus boundaries. For the abelian U(1) theory, we find that the set of states that can be prepared exactly coincides with the set of stabilizer states, which are characterized by quantum error correcting codes. For the nonabelian SO(3) theory, we find that any state can be prepared to arbitrary precision, giving rise to a notion of state universality. We conclude with some final observations to support the idea that entanglement gives rise to the connectedness of spacetime. We study the partial transpose of the thermofield double (TFD) state geometrically, and we demonstrate that local time reversal (which is unitarily equivalent to partial transpose) leads to inconsistencies in the connected spacetime dual to the TFD state.
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Online 20. Searching materials for novel physics from theory and from data [electronic resource] [2018]
 Zhou, Quan.
 2018.
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Materials search and discovery is crucially important in condensed matter physics. Besides experimental trialanderrors, there exist two types of methods to guide materials explorations: "from theory" that starts from theoretic analysis and numerical simulations, and "from data" that leverages massive materials data via statistical machine learning. I will present one work for each of both methods of materials discovery in this dissertation. Firstly, I will discuss the theoretic proposal and materials realization of antiferromagnetic Dirac semimetal. I will specifically show how a nonsymmorphic crystal symmetry stabilizes a fourfold degenerate point in the electronic band structure of an antiferromagnetic system that is invariant under the combination of timereversal and inversion symmetry, thus realizing massless Dirac fermions as low energy excitations. Secondly, I will talk about how to learn atoms' properties from extensive materials data, inspired by ideas from computational linguistics. I will present analysis of the constructed atom vectors, as well as their applications in databased materials prediction using machine learning.
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Online 21. Stringy nonlocality and black hole physics [2018]
 Dodelson, Matthew, author.
 [Stanford, California] : [Stanford University], 2018.
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We analyze nonlocal effects in string theory near black hole horizons. Due to extended string effects, early infalling matter can be detected by late observers long after they fall into the black hole. The nonlocal effects are derived via an analysis of the sixpoint string scattering matrix in flat space, as well as by probing the scattering with a background dilaton. We also derive simple new string solutions in three dimensions.
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Online 22. Thermalization near integrability in a dipolar quantum Newton's cradle [electronic resource] [2018]
 Tang, Yijun.
 2018.
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Ultracold atomic gases are powerful platforms for studying isolated, nearly ideal quantum systems. Recent advancements in laser cooling and trapping of magnetic lanthanide atoms have introduced magnetic dipoledipole interaction into the toolbox of ultracold atomic physics. When coupled with the shortranged Van der Waals interaction, the longranged and anisotropic dipolar interaction dramatically modifies the atomic gas properties. This thesis presents experimental studies of ultracold gases of dysprosium (Dy)  the most magnetic atom. We measured the strength of the Van der Waals interaction in bosonic gases of Dy. Furthermore, we studied how the interplay between the Van der Waals and the dipolar interactions affects expansion dynamics in thermal Dy gases. We have also characterized the anisotropic atomic polarizability near the Dy 741nm narrowline transition. These measurements led to the creation of the first dipolar quantum Newton's cradle, with which we studied thermalization in a nearly integrable onedimensional gas with a tunable integrability breaking dipolar interaction.
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Online 23. Thin silicon and metalassisted chemical etching for photovoltaic and electronic devices [2018]
 Lai, Ruby A., author.
 [Stanford, California] : [Stanford University], 2018.
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Ultrathin silicon membranes, less than 20um thick, have extreme flexibility, lightness, and the superior materials quality and advantages in silicon microprocessing. There are two major roadblocks in developing ultrathin silicon membranes: the fabrication processing of the more delicate material in traditional CMOS fabrication, and the manufacturing of high quality, ultrathin sheets from bulk Si material. First, I use alkaline silicon etching of silicon wafers to form ultrathin silicon sheets, supported by a thick ring of Si material on its edge, that enable facile processing of large 3" sheets in traditional CMOS apparatuses. Second, I explored the novel use of a "chemical wafersaw" for silicon by using metalassisted chemical etching, as a possible pathway to create thin silicon sheets. Third, I developed a new theoretical model for the mechanism of metalassisted chemical etching of silicon, which explained for the first time the silicon doping dependence of the etch. Fourth, I present computational design and fabrication of a novel nanophotonic solar cell contact for a metalinsulatorsemiconductor solar cell, as well as other nanostructures, fabricated using metalassisted chemical etching.
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Online 24. Aspects of cosmology and black hole physics in string theory [electronic resource] [2017]
 Wenren, Danjie.
 2017.
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Over the past few decades string theory has provided us with many novel ideas and models of physics where the interplay of gravity and quantum mechanics is crucial. In particular it has been widely used in the study of black hole physics and cosmology. This thesis describes three aspects of string theory's application in these two fields. First we consider open string pair production effects near hyperbolic black holes in Antide Sitter space (AdS). It is shown that these black holes can decay by radiating Dbranes and there can be nonadiabatic pair production of open strings stretched between those radiated branes. In the second part we switch to cosmology, where we consider two models inspired by axion monodromy, which is very natural in string theory. First we study heavy fermion production effects, which come from the assumption that the fermion mass is modulated by the inflaton field, and its signature on primordial Nspectra. A detailed comparison between this effect and the effect of boson production is made. Lastly, we consider the case where there are a large number of axions that collectively drive inflation. It is shown that the spectral index and the tensortoscalar ratio depend on the distribution of parameters of the axion fields. This thesis is based on papers [1, 2, 3].
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Online 25. Atomistic modeling of highpressure silica crystallization under dynamic compression [electronic resource] [2017]
 Shen, Yuan.
 2017.
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Understanding the kinetics of shockcompressed SiO2 is of great importance for mitigating optical damage for highintensity lasers and for understanding meteoroid impacts. Experimental work has placed some thermodynamic bounds on the formation of highpressure phases of this material, but the formation kinetics and underlying microscopic mechanisms are yet to be elucidated. In this study, by employing multiscale molecular dynamics studies of shockcompressed fused silica and quartz, we find that silica transforms into a poor glass former that subsequently exhibits ultrafast crystallization within a few nanoseconds. We also find that, as a result of the formation of such an intermediate disordered phase, the transition between silica polymorphs obeys a homogeneous reconstructive nucleation and grain growth model. We construct a quantitative model of nucleation and grain growth, and compare its predictions with highpressure silica crystal grain sizes observed in laserinduced damage and meteoroid impact events. Moreover, we have studied the quantum nuclear effects for highpressure silica crystallization. While quantum nuclear effects play important roles in shockinduced chemical reactions and phase transitions, they are absent in classical atomistic shock simulations. To address this shortcoming, we couple the shock simulation with a colorednoise Langevin thermostat. We find that this semiclassical approach gives shock temperatures as much as 7% higher than classical simulations near the onset of crystallization in silica. We have also studied the impact of this approach on the kinetics of crystallization and the position of highpressure silica melt line.
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Online 26. Automorphy, geometry, and symmetries of BPS states [electronic resource] [2017]
 Paquette, Natalie M.
 2017.
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A host of new observations regarding BPS states in supersymmetric string compactifications point towards tantalizing new mathematical structures underlying string theory. The mathematical subjects of finite group theory, number theory (especially modular and mock modular forms), vertex operator algebras, generalized KacMoody algebras, enumerative geometry, and more have come to the fore in string theory of late, prompted in part by the ``Mathieu moonshine" observation in 2010 by Eguchi, Ooguri, and Tachikawa. This thesis describes progress in understanding mathematical aspects of string compactifications, with a focus on Mathieu and Umbral moonshines, automorphic forms, manifolds of special holonomy, and the algebraic and symmetric properties enjoyed by BPS subspaces of string theory. We make progress towards using string theory as an explanatory framework that ties together some of these mathematical disciplines. We also employ new mathematical ideas to constrain and describe highly symmetric string vacua.
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3781 2017 P  Inlibrary use 
 Gu, Yingfei.
 2017.
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The butterfly effect, as an icon for the chaotic dynamics, refers to the exponential sensitivity on the initial conditions. This phenomenon is common in daily life, e.g. it explains the difficulty of long time weather reports. For physicists, the idea of the chaotic dynamics helps to understand the ergodicity of a classical complex system and therefore is essential for the statistical mechanics and thermodynamics. In the microscopic manybody systems governed by quantum mechanics, the chaotic dynamics is also expected to be generic and ultimately helpful for the understanding of the quantum thermalization. What I will show in this dissertation is that the quantum butterfly effect could also provide precise information about the nontrivial properties of the manybody interacting systems, such as thermal transport and topological properties. I will employ two classes of solvable models: the SachdevYeKitaev model in high dimensions and the rational conformal field theories in two dimensions to explicitly present the unexpected connection between the butterfly effect and other aspects of the model.
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Online 28. Constructing scattering amplitudes from their formal properties [electronic resource] [2017]
 McLeod, Andrew.
 2017.
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Scattering amplitudes in quantum field theory encode the probability of configurations of incoming and outgoing particles scattering into each other, as well as particle masses and decay rates. Traditionally they have been calculated using Feynman diagrams, but this method generally proves too computationally intensive to allow for the calculation of higherloop contributions, which are relevant for making predictions in particle physics experiments and to our understanding of quantum field theory itself. As a step in the direction of filling this computational gap, this dissertation presents an improved bootstrap method for computing scattering amplitudes in the planar limit of maximally supersymmetric YangMills theory. This method does away with Feynman diagrams altogether, and instead uses knowledge of the symmetries and analytic properties of scattering amplitudes, in conjunction with an understanding of the mathematical form these amplitudes take in general and special kinematics, to uniquely determine them at high loop orders. In particular, it makes use of the fact that amplitudes in this theory are expressible in terms of generalized polylogarithms for seven and fewer particles. The first part of this dissertation focuses on sixparticle kinematics, where previouslyunappreciated algebraic constraints on these amplitudes are described that restrict both their double derivatives and their double discontinuities. Alongside previouslyunderstood constraints, these properties are used to uniquely determine all sixparticle amplitudes in this theory through five loops. These explicit results are then used to provide analytic and numerical evidence for a recentlyconjectured positivity property these amplitudes are thought to have in certain kinematic regions. In the second part of this dissertation, it is shown that these methods straightforwardly generalize to sevenparticle kinematics, where they in fact prove to be even more restrictive than in sixparticle kinematics. In particular, a smaller set of constraints is shown to be sufficient to determine specific sevenpoint amplitudes at three and four loops, up to integration constants. While the results presented in this thesis are confined to the planar limit of maximally supersymmetric YangMills theory, these bootstrap methods are expected to prove useful even in theories without supersymmetry.
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Online 29. Couplings of phonons to light and one another studied with LCLS [electronic resource] [2017]
 Henighan, Thomas.
 2017.
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Engineering the thermal properties of materials plays a crucial role in technologies including propulsion, computing, optics, and household appliances. Lattice vibrations, or phonons, are at the heart of our understanding of heat in solids. It is thus beneficial to continue exploring the basic science of phonons not only for the purpose of expanding human knowledge, but for making possible further advances in materials engineering as they pertain to heat. Fundamental to the theory of phonons is the phonon dispersion, the relationship between phonons' momentum and their energy. Momentum resolved inelastic scattering of neutrons and xrays provides experimental access to this dispersion [1, 2]. An accurate measure of a material's phonon dispersion can allow for accurate prediction of its heat capacity, interatomicbonding strengths, and sound propagation speed amongst other things. However the phonon dispersion gives us no direct information on how phonons couple to other excitations and/or one another, which is important for macroscopic thermal properties. For instance thermal expansion and finite thermal conductivity are consequences of finite phononphonon coupling. Current methods for measuring such interactions are indirect, including measurement of phonon linewidths and measurements of thermal conductivity. Timeresolved measurements can be useful for measuring couplings by observation of energy transfer between excitations with time. Thus a time and momentum resolved measure of phonons would seem an obvious tool for studying their couplings to one another and other excitations. While optical measurements can provide exquisite time resolution, they can resolve only very small momentum shifts. Traditional neutron and xray sources have the necessary momentum resolution, but the pulses are too long (~100 picoseconds or more) to resolve the transfer of energy of picosecond timescales, relevant to phononphonon coupling. Plasmabased xray sources have su cient momentum and time resolution, but the flux is too low to measure weak di↵raction signals from phonons in a reasonable amount of time. The Linac Coherent Light Source (LCLS) is the first instrument to provide all the aspects neces sary for time and momentum resolved measurement of phonon energy transfer, with shortwavelength (~1 angstrom), shorttime (~10s of femtoseconds) pulses at high flux (~10^13 photons/second) [3]. Trigo et al showed that this new tool can be used to measure phonon dispersions in a timeresolved way [4]. Specifically, they showed that a short optical pump can be used to excite temporal coherences for phonons throughout the Brillouin zone that can be observed in the timeresolved xray scattering from a delayed LCLS xray pulse. The work of this thesis was motivated by the desire to use LCLS to make fundamentally new measurements of phonon coupling. To do this we use variations of the technique of Trigo et al. We first explore further the principles behind the technique, specifically the mechanism by which short wavelength light couples to highwavevector phonons. We find that the opticalphonon copuling is of second order in the phonons, exciting correlated pairs of phonons with nearly equal and opposite momentum. Next, we explore a method for measurement of energy transfer in the parametric downconversion of a zonecenter phonon in crystalline bismuth. The result is, to our knowledge, the first time and momentum resolved measurement of phonon decay channels. Finally, we show that a shaped optical pump pulse may be used to achieve frequencyselective excitation of the phonons. Taken together, these results suggest tools like LCLS may be used to make measurements of phononphonon coupling strengths that were previously inaccessible experimentally.
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Online 30. Depth perception in holography [electronic resource] [2017]
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According to the holographic principle, information about our world can be encoded in a projection of one less dimension, similar to a hologram. This principle has culminated in the discovery of the AdS/CFT duality, an explicit example of holography where, miraculously, the lowerdimensional projection is a theory of familiar local fields. But how is the extra dimension encoded in this holographic theory? The equivalence between a gravitational theory and a lowerdimensional theory implies a radical reorganization of the degrees of freedom: the fundamental building blocks of a gravitational theory are likely extended, not pointlike, objects. In this thesis, I describe progress towards formulating both sides of the duality in terms of extended probes  objects which naturally possess the ability of "holographic depth perception.".
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3781 2017 M  Inlibrary use 
 Desmond, Harry.
 2017.
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Dark matter halos comprise the bulk of the universe's mass, yet must be probed by the luminous galaxies that form within them. A key goal of modern astrophysics is to robustly relate the visible and dark mass, which to first order means relating the properties of galaxies and halos. The aim of this thesis is to develop and evaluate models of the galaxyhalo connection using observations of galaxy dynamics. In particular, I build empirical models based on the technique of halo abundance matching for five key dynamical scaling relations of galaxies  the TullyFisher, FaberJackson, masssize and mass discrepancyacceleration relations, and Fundamental Plane  which relate their baryon distributions and rotation or velocity dispersion profiles. I then develop a statistical scheme based on approximate Bayesian computation to compare the predicted and measured values of a number of summary statistics describing the relations' important features. I find some features to be naturally accounted for by an abundance matching approach and others to impose new constraints on the galaxyhalo connection; the remainder are challenging to reproduce and may imply galaxyhalo correlations beyond the scope of basic abundance matching. Besides providing concrete statistical tests of specific galaxy formation theories, these results will be of use for guiding the inputs of empirical and semianalytic galaxy formation models, which require galaxyhalo correlations to be imposed by hand.
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Online 32. A Fermi liquid perspective on the high field ground state of the cuprate superconductors [electronic resource] [2017]
 Maharaj, Akash V.
 2017.
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The nature of the parent metallic state from which high temperature superconductivity emerges has remained fiercely controversial in the three decades since the discovery of the cuprate superconductors. Surprisingly, recent experiments in magnetic fields high enough to quench superconductivity have revealed a metallic state whose properties are remarkably conventional, and well explained within the context of Fermi liquid theory. Yet, even within this paradigm, these experiments have raised several fundamental theoretical questions. This thesis focuses on a few such experimentally motivated matters of theoretical principle. The primary themes involve issues surrounding quantum oscillations, as well as the recent discovery of charge density waves (CDWs) in the underdoped cuprates. I begin with a discussion of how charge density waves in YBCO can be related to earlier discovered stripes in the `214' family of cuprates, and also consider the experimental consequences of the resulting vestigial orders which break discrete rotational and/or mirror symmetries. I show that Xray scattering measurements of seemingly biaxial CDW order, can in fact originate from a three dimensional `crisscrossed' pattern of stripes. This three dimensional pattern breaks mirror symmetries, leading to sharp consequences for quantum oscillation spectra, possible detection in elastoresistance experiments, and each of these topics form chapters of this thesis. The discussion of quantum oscillations starts by considering whether they are even possible in the presence of incommensurate CDWs that formally destroy translation symmetry, rendering the concept of a Fermi surface approximate at best. Using exact dualities, I show that quantum oscillations are no longer periodic in 1/B, and even disappear for sufficiently strong incommensurate CDWs. In a subsequent chapter, I use similar dualities to constrain the form of the Fermi surface that is possible in YBCO, and discuss the strong evidence for both mirror symmetry breaking and significant quasiparticle renormalization. Finally, I examine the behavior of the Hall number of a metal when nematicity results in a Lifshitz transition where the Fermi surface topology evolves from a closed pocket to open sheets. I provide analytic expressions for the critical behavior of the Hall number, and also relate these results to recent experiments in the cuprates. I conclude this thesis by synthesizing these ideas into a proposed doping evolution for the Fermi surface of an idealized cuprate.
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Online 33. Field theory for cosmology [electronic resource] : an effective approach [2017]
 Perko, Ashley Nicole.
 2017.
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Effective field theory (EFT) is our most successful tool to date for exploring the fundamental processes of particle physics: it has been able to describe all know particle interactions in the lab to astonishing accuracy. We are now entering an era of precision cosmology, where we can use the power of EFT, a tool that has only recently been applied to the field of cosmology, to fully make use of cosmological observations. This thesis comprises recent work applying effective field theory in the context of earlyuniverse cosmology and largescale structure (LSS).
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Online 34. High brightness electron beams for fourth generation light sources [electronic resource] [2017]
 Garcia, Bryant William.
 2017.
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In this dissertation, we examine the production and preservation of high brightness electron beams for fourth generation light sources. The relentless push toward brighter photon pulses from Free Electron Lasers (FELs) has been facilitated by an increase in the brightness of the driving electron beam. One method of increasing this brightness is to provide an electron beam which is prebunched at the FEL wavelength, thereby providing a fully coherent seed for the lasing process. We explore the technique of EchoEnabled Harmonic Generation (EEHG) to seed the electron beam at a high harmonic wavelength of a conventional, fully coherent laser pulse. We build on the previous work at the Next Linear Collider Test Accelerator (NLCTA) to extend the harmonic upconversion via EEHG to the 75th harmonic and demonstrate the ability to create multicolor, tunable bunching spectra using a chirped electron beam and the EEHG technique. We also examine with detailed numerical simulations the interplay between the microbunching instability and EEHG. Additionally, we develop a theoretical model for a novel source of emittance degradation due to a stochastic addition to the standard Coherent Synchrotron Radiation field. This effect is found to grow with both electron beam energy and density, potentially limiting the ultimate brightness of some electron beams. Physically, the effect is found to be due to the stochastic scattering of electrons off the narrowangle synchrotron radiation cones of other electrons as they traverse a bend magnet. This novel effect is another manifestation of the difficulties posed as the electron beam brightness is continually increased.
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Online 35. High pressure study of metal chalcogenides [electronic resource] [2017]
 Zhao, Zhao.
 2017.
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Twodimensional (2D) materials, topological insulators (TIs), and sesquioxides have attracted huge research interest recently due to their scientific and industrial importance. The study of these materials explores the fundamentals of condensed matter physics while also shedding light on potential applications such as optoelectronics and spintronics. Pressure is an important thermodynamic parameter in changing structural and electronic configuration of a material, which can dramatically alter material properties. The integration of multiple in situ experimental probes with a diamond anvil cell enables the investigation of structural and electronic tuning of a material, exploration of novel high pressure phases, and optimization of material performances. This dissertation focuses on the effect of pressure on three systems in metal chalcogenides. First, the high pressure behavior of a representative 2D material molybdenum diselenide (MoSe2) was studied up to 60 GPa. Upon compression, MoSe2 evolves from an anisotropic 2D layered network to a threedimensional (3D) structure without a phase transition, which is different from the case of MoS2. The role of the chalcogenide anions in stabilizing different layered patterns is underscored by our layer sliding calculations. MoSe2 possesses highly tunable transport properties under pressure, determined by the gradual narrowing of its bandgap followed by metallization. The continuous tuning of its electronic structure and bandgap in the range of visible light to infrared suggests possible optoelectronics applications. Second, the high pressure behavior of potential TIs silver chalcogenides (Ag2X, X = S, Se, and Te) were studied up to 40 GPa. Under pressure, Ag2X exhibits a series of structural transitions and an increase in Ag to nearby X coordination number. Interestingly, a triple layer stacking pattern appears while the existence of two Ag crystallographic sites is maintained. Phase Is of Ag2Te and of Ag2Se are proposed as TIs from the bandgap increase under pressure and band structure calculations. Higher pressure induces metallization of Ag2X where large electronic evolution occur, for example, phase II of Ag2Te is found to be bulk semimetallic with topological nontrivial nature while phase III of Ag2Te becomes bulk metallic. Strong changes in infrared transmittance and reflectivity support the changes in their electronic structures. The results demonstrate silver chalcogenides as candidate materials for study of pressure induced TI to nonTI transitions under pressure. Third, the high pressure behavior of XV group sesquioxide αSb2O3 was investigated up to 50 GPa. During compression, a firstorder structural transition occurs at ~ 15 GPa, where the "molecular" cubic Sb2O3 phase I gradually transforms into a layered tetragonal phase II through local distortions and symmetry breaking. Firstprinciples calculations indicate that the bandgap decreases dramatically from phase I to phase II, consistent with changes in sample color and transparency. At higher pressure, a sluggish amorphization process occurs. Our results highlight the structural connections between late XV group sesquioxides and the role of the lone electron pair in determining local structures under pressure. These results underscore pressure as a powerful tool for modifying the lattice and electronic structure of metal chalcogenides and influencing their material properties.
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Online 36. Holographic duality and random tensor network [electronic resource] [2017]
 Yang, Zhao.
 2017.
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Holographic duality is a proposed correspondence between quantum manybody systems living on the conformal boundary of an asymptotically antide Sitter space and the quantum gravity living in one higher dimension in the bulk. A particularly interesting aspect of this duality is played by the quantum entanglement. According to the RyuTakayanagi formula, the entanglement entropy of a boundary region corresponds to the area of the minimal surface bounding this region, which agrees with the entropy properties of the tensor network states. This dissertation aims to build concrete relations between the holographic duality and the tensor networks. We first propose the concept of the bidirectional holographic code, which means all the boundary states can be represented in the bulk while the states within a constrained code subspace play the role of "classical geometries". We implement the bidirectional holographic code explicitly using the random tensors, which generates a class of solvable tensor network models that reproduce many properties of the holographic duality. We further generalize the random tensor network approach to allow quantum superposition of di erent spatial geometries, which moves one step towards the quantum description of the gravity theory. Lastly, we study the dynamical properties in the holographic duality using the tensor networks and find that the quantum error correction properties bridge the lightcone structure in the bulk and the buttefly velocity (i.e. the speed of chaos propagation) on the boundary.
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Online 37. Hybrid ionic liquid  boron nitride gates for clean, high carrier density transistors [electronic resource] [2017]
 Petach, Trevor.
 2017.
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Using gates to change carrier density via the electric field effect is a cornerstone of condensed matter physics. Gating using ionic liquid electrolytes has recently generated considerable interest as a method to achieve large carrier density modulations in a variety of materials, opening routes to devices based on physics accessible only at carrier densities beyond the breakdown limit for oxide dielectrics. However, electrolyte gates can chemically modify the channel due to electrochemically driven reactions and increase carrier scattering due to the proximity of the ions in the electrolyte to the carriers in the channel. In this work, I discuss how inserting a thin layer of hexagonal boron nitride between the electrolyte and the channel prevents chemical modification and suppresses scattering, while still allowing carrier densities significantly beyond those possible with oxide dielectrics. I begin with a brief introduction to electrolyte gating using ionic liquids, including the use of reference electrodes in three terminal measurements. In the second chapter, using a combination of in situ xray spectroscopy and electrochemical techniques, I show that trace impurities in the ionic liquids can cause reversible electrochemical oxidation of a gold channel and that a thin boron nitride layer prevents this oxidation. I then take a brief digression to discuss how xray scattering can be used to learn about surface and interface structure. I develop a new model for analyzing crystal truncation rods from miscut surfaces that can be used to learn about terrace morphology and that has a simple roughness factor to account for disorder from terrace steps in the truncation rod intensity. In the fourth chapter, I use xray reflectivity to probe the spatial arrangement of the ions on a strontium titanate channel, and show that the timescale for ion rearrangement matches the timescale for the onset of electrical conduction, suggesting an electrostatic gating effect. Finally, I show that boron nitride spacers significantly improve carrier mobility in graphene channels and that the remaining scattering arises primarily from ions in the bulk liquid.
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Online 38. Identification of single barium atoms with resonance ionization mass spectroscopy for the nEXO neutrinoless double beta decay experiment [electronic resource] [2017]
 Kravitz, Scott.
 2017.
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The mechanism for neutrino mass generation is an open question in particle physics, with implications for new physics at higher mass scales. If neutrinos are their own antiparticle, meaning they have Majorana masses, this property can be measured through a rare process called neutrinoless double beta decay. EXO200 is an experiment searching for neutrinoless double beta decay of xenon136 using a liquid xenon time projection chamber. The first part of this work describes a search for the twoneutrino double beta decay of xenon136 to an excited state of barium136 with EXO200 data using machine learning techniques. A measurement of the halflife of this decay can provide valuable input to nuclear models and reduce systematic uncertainties of the neutrinoless double beta decay process. The second part of this work describes efforts to greatly improve the sensitivity of a future experiment similar to EXO200 through the identification of the barium136 daughter produced in the double beta decay of xenon136. In the technique explored here, barium ions are adsorbed onto a substrate, where they neutralize, and are then transported to a separate identification chamber. They are subsequently desorbed using laserinduced thermal desorption (LITD) and selectively ionized using resonance ionization spectroscopy (RIS), followed by identification using a time of flight mass spectrometer. Improvements in understanding of the LITD and RIS processes, backgrounds to the technique, and substrate cleaning methods are presented, bringing the technique closer to single barium atom sensitivity.
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Online 39. Imaging of electron forces, interactions, and topological states in designer quantum materials [electronic resource] [2017]
 Rastawicki, Dominik.
 2017.
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We have developed atomic manipulation with a scanning tunneling microscope (STM) into a compelling new tool to investigate the fundamental properties of condensed matter systems. Our new capability to assemble and finetune essentially any twodimensional lattice combined with the ability to probe density of states at subatomic scale allows us to investigate the physics of electronic states with unprecedented freedom and precision. Here I aim to answer questions that so far proved too elusive for traditional material synthesis and measurement methods, in particular, questions about topological states in complex nonperiodic systems and about manybody instabilities driven by electron interactions. In this thesis, I focus on corrals and lattices created by patterning a free electron gas of a Cu(111) surface with carbon monoxide (CO) molecules. The CO molecules provide act as potential wells and constrain the surface state electrons to an effective lattice or corral pattern. In the first part I explain a series of quantum force measurement experiments, where I try to shed some light on the quantum force distance dependence and focusing inside several corral structures. Next part describes charge fractionalization in molecular polyacetylene as well as in Kekule distorted molecular graphene. I discuss how a domain wall or a vortex defect in a bond strength wave, leads to an emergence of a midgap state, and the fractional charge associated with it. Following that, I talk about effective gauge fields in graphene induced by strain as well as through direct modulation in bond strength and onsite potential. I explain how these induced perturbations to the lattice can be described by gauge fields, equivalent to the ones associated electromagnetic fields. One remarkable consequence of this equivalence is strain gauge invariance that allows one to produce lattices with the same electronic energy spectrum, but very different local structure. In the next part, I show how electronelectron interactions lead to instabilities as the lattice constant changes. In particular, I show that in a honeycomb lattice doped to the Van Hove singularity, the instability leads to a spontaneous nematic and polarized pseudospin phase. I also research investigate the instability in the flat band of a honeycomb 558 grain boundary where the leading phase is likely magnetic. Next, I describe quasicrystalline molecular lattices based on Penrose tilings and the electron fractalization that happens in them. I show the deep connection between penteract and electrons in a KiteandDart quasicrystal that form localized states at energies related by the golden ratio. I end by briefly discussing some possible future experiments that can exhibit an even larger variety of effects such as an emergence of a quantum spin Hall state or topological currents can be expected. These effects might show when one introduces stronger interactions and stronger spinorbit coupling present for example on surfaces of gold and topological insulators.
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Online 40. Novel phenomena in topological states of matter [electronic resource] [2017]
 Lian, Biao.
 2017.
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Topological states of matter exhibit properties that are protected by certain topological invariants and are invariant under perturbations. Depending on whether they have an excitation gap or not, these topological states can be classified into gapped and gapless phases. In this thesis, we first discuss the novel properties and recent developments of two kinds of gapped topological states in twodimensions (2D): the quantum anomalous Hall (QAH) insulator and the chiral topological superconductor (TSC), which can be realized in thin films of 3D topological insulators. In particular, we identify the presence of a zero Hall conductance plateau and a unique half plateau of twoterminal conductance in the QAH state and the chiral TSC state, respectively, both of which are confirmed by experiments. In the second part, we present two novel kinds of gapless topological states of matter characterized by linking numbers: the 5D Weyl semimetal and the 3D time reversal invariant superconductor with linked nodal lines, which show interesting bulkboundary correspondences and topological responses.
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3781 2017 L  Inlibrary use 
 Lamprou, Lampros.
 2017.
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The quantum physics of black holes and advances in string theory indicate that our contemporary notion of space—a continuous dynamical geometry obeying Einstein's equations—is an emergent concept. Gravitational physics appears instead as an effective description of a lowerdimensional quantum mechanical theory. This idea is called the holographic principle. In this thesis, we make steps towards developing a mathematical language for describing the emergence of geometry in the AdS/CFT correspondence, a stringtheoretic realization of the holographic principle. The key idea we exploit is the curious relation between spacetime geometry and quantum entanglement discovered by Ryu and Takayanagi. We import mathematical tools from the field of integral geometry to connect questions such as "What is a point?" and "What is a distance?" in AdS space with the entanglement pattern of the CFT wavefunction. We then utilize the previous formalism to propose a new way of linking the degrees of freedom on the two sides of the AdS/CFT duality.
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3781 2017 L  Inlibrary use 
 Nie, Laimei.
 2017.
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Strongly correlated electronic systems have stimulated numerous developments in theoretical frameworks, numerical tools, and experimental techniques. One group of materials that have been attracting meticulous efforts is the hightemperature (highTc) superconductors, not merely due to its large transition temperature, but also because it offers a well characterized laboratory for the study of exotic phenomena such as quantum criticality and nonFermi liquid behavior. One pressing question in the field is the role played by disorder: inevitable in real materials, disorder is able to fundamentally alter the properties of system under certain circumstances. This thesis studies, from a theoretical point of view, how disorder affects various electronic orders in several model highTc superconductors, in particular copperbased highTc materials (cuprates). Various recent experiments in these materials are readily interpreted in light of our results.
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3781 2017 N  Inlibrary use 
 Zipp, Lucas John.
 2017.
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This dissertation explores two major lines of research concerning ultrafast electron dynamics in atoms and molecules. The first part investigates the dynamics of photoionization in intense laser fields on the attosecond time scale. A new technique using a weak probing field at half the frequency of the strong ionizing laser field reveals attosecond delays in the abovethreshold ionization process. We observe the influence of the combined Coulomblaser potential on the spectral phase of the photoelectron. In the second part, an experiment which imaged the uncoupling of electron motion from the molecular frame in rotating molecules is described. A coherent wave packet in the 4f Rydberg manifold of molecular nitrogen is created and its motion is probed in time. This allows for a direct observation in the time domain of a nonBornOppenheimer regime, known as the luncoupling regime, that up until now has only been inferred from spectroscopic data.
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Online 44. Search of new physics with boosted higgs boson in hadronic final states with ATLAS detector [electronic resource] [2017]
 Zeng, Qi.
 2017.
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The discovery of a Higgs boson at the Large Hadron Collider (LHC) confirms the validity of the Standard Model (SM) in the description of particle interactions at electroweak scale. However, radioactive corrections to the Higgs mass drives its value to the model's validity limit, indicating either extreme finetuning or the presence of new physics at higher energy scale. Since 2015, the LHC starts its Run 2 journey with unprecedented center of mass energy of 13 TeV. Along with increase in luminosity, this greatly extends the sensitivity of ATLAS experiment to heavy new particles at TeV scale. In particular, many new physics models beyond the Standard Model manifest themselves through significant coupling to the Higgs boson in decays of new particles to a Higgs boson and other SM particles. In this work, two searches for resonances decaying to either pair of Higgs bosons or a Higgs boson associated with another SM vector boson in all hadronic final states are presented using data collected by ATLAS during Run 2. Due to the heavy mass of new resonance, Higgs boson and W/Z boson can be boosted to large momentum, causing their decay products to be collimated. The dominant H> bb decay mode also provides a clear signature through displaced vertices. A powerful boosted boson identification technique fully exploiting such jet substructure and heavy flavor information is therefore developed and used in both searches to suppress the dominant multijet backgrounds and largely enhance search sensitivity in particular for very high resonance mass. In the absence of significant excess, new exclusion limits are set on benchmark new physics models.
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3781 2017 Z  Inlibrary use 
 Huang, Junwu.
 2017.
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This thesis discusses a framework in which Weinberg's anthropic explanation of the cosmological constant problem also solves the higgs hierarchy problem. The weak scale is selected by chiral dynamics that controls the stabilization of an extra dimension. When the higgs vacuum expectation value is close to a fermion mass scale (the weak scale), the radius of an extra dimension becomes large, and develops an enhanced number of vacua available to scan the cosmological constant down to its observed value. At low energies, the radion, the particle that controls the size of the extra dimension, necessarily appears as an unnaturally light scalar, in a range of masses and couplings accessible to fifthforce searches as well as scalar dark matter searches with atomic clocks and gravitationalwave detectors. The fermion sector that controls the size of the extra dimension consists of a pair of electroweak doublets and several singlets. These leptons satisfy approximate mass relations related to the weak scale and are accessible to the LHC and future colliders.
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Online 46. Strain control of single crystal complex oxide epitaxial and freestanding films [electronic resource] [2017]
 Lu, Di.
 2017.
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Many breakthroughs in condensed matter physics, including high Tc superconductivity, colossal magnetoresistance and multiferroics, originate from the study of transition metal perovskite oxides. Epitaxial strains on oxides can significantly alter these properties and realize novel functionalities, yet switching substrates not only changes the strain states of the film, but also affects the defect type and density in the film. In parallel with oxides, the recent development in exfoliated layered materials opens a new pathway of material manipulation, such as large strain or anisotropic strain application, due to their extreme geometry. However, creating exfoliatedmateriallike oxides has also proved challenging, limiting the manipulation capabilities of these oxides. This thesis is devoted to addressing these two limitations of epitaxial strain application for oxide films. In the first part, I will demonstrate that strain states and physical properties of oxide thin films can be controlled without affecting film quality by using Sr3Al2O6 epitaxial buffer layers. Sr3Al2O6 has lower elastic moduli than common oxides, which allows it to confine the mismatch dislocations to itself but not propagate to the overlaying films, preserving their quality. To show that the Sr3Al2O6 buffer layers are ideal for controlling physical properties of high quality oxide thin films, strain and qualitysensitive Nd0.5Sr0.5MnO3 films are employed. By controlling the thickness of Sr3Al2O6 buffer layers, the (001)oriented Nd0.5Sr0.5MnO3 films are tuned from a ferromagnetic metal to a insulator with low magnetization. By carefully tuning the strain state, a bulklike ferromagnetic metal to chargeordered insulator phase transition is also realized, which has previously proven to be difficult for (001)oriented Nd0.5Sr0.5MnO3 films. In the second part, I will present a general method of fabricating oxide freestanding films, i.e. single crystal oxide thin films free from substrates. The key is to insert a sacrificial layer, again Sr3Al2O6, between an epitaxial oxide film and a substrate while keeping the epitaxial relation. The sacrificial layer was etched afterwards by room temperature water, and millimetersized high quality freestanding oxide films were obtained. As an example of demonstrating novel strain manipulation methods, I will also show how physical properties of SrTiO3 freestanding films can be changed by external strain application. The ground state of SrTiO3 is at the boundary of a paraelectric state and a ferroelectric state, and perturbation of its lattice can elevate the ferroelectricparaelectric phase transition to nonzero temperature, where a maximum of dielectric constant is observed. By applying uniaxial stress, longitudinal strains of up to 1% can be generated in this system, the dielectric maxima were observed near 300 K, suggesting such a phase transition. Our studies establish Sr3Al2O6 buffer layers and oxide freestanding films as two general tools that can be used to broaden the strain manipulation methods on oxides, which has significant potential of drastically altering their physical properties.
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Online 47. A study of Fermi surfaces in strongly interacting quantum field theories via holoraphy [electronic resource] [2017]
 Martin, Victoria Lynn.
 2017.
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The motivation for this work is to obtain a holographic description of strongly interacting quantum field theories that exhibit Fermi surface behavior at low energies. A first step towards this is to determine the contexts in which Fermi surfaces are manifest holographically  that is, which theories of gravity with holographic duals contain low energy degrees of freedom that exist at nonzero momentum. The spectral weight is an important field theoretic quantity that acts as a spectral weight diagnostic:it directly counts the number of degrees of freedom at a given frequency and momentum. Calculating a nonzero value for the spectral weight at low energy and over a finite range of momenta is a signature of a Fermi surface. In what follows, I introduce the calculation of the low energy spectral weight in three holographic theories: the semilocal quantum liquid, the D3/D5 brane system and the holographic superfluid. In the semilocal quantum liquid theories, we discover nonzero low energy spectral weight over a finite range of momenta, and attribute this Fermi surface behavior to the charges existing behind the black hole horizon. Contrary to our expectations, we also obtain nonzero spectral weight in the holographic superfluid case, complete with a bulk instability indicating that the theory is not in the true ground state. We offer an interpretation of these findings, and present interesting questions that arise regarding the connection between the bulk and boundary charge distributions.
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Online 48. Study of nanoscale magnetization dynamics and reversal following ultrafast optical excitation by resonant Xray diffraction [electronic resource] [2017]
 Liu, Tianmin.
 2017.
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In 1996, femtosecond (fs) optical laser pulse was first discovered by as one of the novel methods to quench the magnetization[1]. While the fs optical laser pulses typically induces demagnetization, they are also discovered to be able to cause alloptical switching (AOS) of magnetic domains in the transition metalrare earth (TMRE) alloy GdFeCo[2, 3, 4, 5, 6]. This phenomenon not only opened door for fascinating nonequilibrium magnetism research but also brought forth the possibility of optical control of magnetism in future magnetic recording technologies. In this thesis, we take an microscopic approach to study the opticallyinduced magnetization dynamics by utilizing xray diffraction technique. We are able to address some important physics questions and technological relevancy regarding the phenomenon. The technological potential of AOS has recently increased with the discovery of the same effect in other materials, including REfree magnetic multilayers[7, 8]. However, to be technologically competitive for the bit density requirement of future storage device, AOS must further restrict its opticallyswitched magnetic areas to sizes well below the diffraction limit. By deploying gold plasmonic antenna structure on the surface of ferrimagnetic TbFeCo alloy, we demonstrate reproducible and robust alloptical switching of magnetic domains of 53 nm size. The nanoscale magnetic reversal is imaged both around and beneath plasmonic antennas using xray resonant holographic imaging technique. Furthermore, our results also demonstrate the importance of the sample chemical nanostructure on the magnetic switching. The microscopic dynamics of magnetization following an fs optical excitation is also studied in the similar material GdFeCo. Based on theoretical predictions[9, 10], we searched for magnetic solitons generated from spin wave condensation in the farfromequilibrium condition induced by fs optical excitation. By studying the resonant xray diffraction pattern, we present evidence of such soliton feature formation in magnetization dynamics experimentally. We also relate the microscopic magnetization picture to the bulk magnetization response of the sample.
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Online 49. Theory of fewphoton quantum scattering in nanophotonic structures [electronic resource] [2017]
 Xu, Shanshan.
 2017.
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The capability to create strong photonphoton interaction at a fewphoton level in integrated photonic systems is of central importance for quantum information processing. To achieve such a capability, an important approach is to confine photons in a onedimensional waveguide coupled to a local quantum system with strong nonlinearity. At a fundamental level, photonphoton interaction in such system is described by multiphoton scattering matrix (S matrix). In this thesis, we discuss both computational and conceptual aspects of multiphoton S matrix. For the computational aspect, we provide a systematical way to compute Nphoton S matrix using the inputoutput formalism. The main result is a general connection between the Nphoton S matrix and the Green functions of the local quantum system. Such computation can be generalized straightforwardly to the case of multiple waveguide channels to study the Fano interference in the presence of photonphoton interactions. For the conceptual aspect, we discuss the general structure of twophoton S matrix without explicit computation. Using techniques that are closely related to cluster decomposition principles in quantum field theory, we provide a general constraint on the analytic properties of the twophoton S matrix. Furthermore, we present a generalized form of the cluster decomposition principle. The twophoton S matrix, when the local quantum region supports multiple ground states, has an analytic structure that differs significantly from what is commonly anticipated.
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Online 50. Topological aspects of gapless phases [electronic resource] [2017]
 Bulmash, Daniel.
 2017.
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The development of topological phases of matter has greatly expanded our understanding of what a phase of matter could be. Topological phases have highly robust features; this robustness is typically protected by an energy gap. However, with the recent discovery of Weyl and Dirac semimetals, it has been realized that not only can gapless systems be topologically nontrivial, often with gaplessness itself being topologically protected. This thesis is a theoretical exploration of gapless topological phases from several perspectives. First, we propose that Hg_{1xy}Cd_xMn_yTe can be a timereversalbroken WSM. This proposal has several benefits, including that the singledopant (x=0 or y=0) cases are already very wellstudied, the Weyl points are tunable using magnetic field, and the Hall conductivity behaves highly nontrivially as a function both of temperature and of magnetic field angle. Next, we investigate WSM and DSM thin films, looking for quantum oscillations that involve the Fermi arcs. We extend known results in the weakfield limit, and propose a new experiment with a strong inplane component in the field which has highly unusual dependence of the quantum oscillations on field angle. Inspired by the ensuing theoretical understanding of a 3D metal in a strong magnetic field, we then investigate the effect of interactions on metallic wires subject to the orbital effects of a strong magnetic field. Using an analogy between fermions in the zeroth Landau level and truly 1D fermions with a (potentially large) pseudospin, we are able to apply powerful 1D tools like bosonization to find a plethora of interesting phases. This includes phases where the correlation functions of either charge density wave order or superconducting order obey magnetic fieldtuned power laws, as well as a phase with power law correlations of both pseudospintriplet superconductivity and pseudospindensity wave order. Finally, we construct a framework for unifying the topological response properties of both gapped and gapless free fermion systems by mapping a ddimensional system in real space (gapped or gapless) to a gapped 2ddimensional quantum Hall system in phase space. This allows us to construct a phase space response theory for any free fermion system and to demonstrate that the generic topological feature of a gapless system is a quantized anomaly related to the edge anomaly of the phase space quantum Hall system.
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3781 2017 B  Inlibrary use 
 Mahajan, Raghu.
 2017.
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Weakly perturbing a system by an external force and measuring its response provides us with rich information about the underlying physics of the system. Linear response theory relates experimental quantities such as electrical conductivity and thermal conductivity to twopoint correlation functions of microscopic electric and heat current operators. There is a wealth of experimental data on conductivities. However, on the theoretical front, our knowledge away from the limit of small interparticle forces is poor. In this work, we present some new ideas and calculations that further our theoretical understanding of electric and heat transport when the interparticle forces are strong. In chapter 1, we set up our notation, define various twopoint correlation functions and derive the Kubo formula, paying special attention to subtleties that are often glossed over in many texts. In chapter 2, we derive an upper bound on diffusion that follows via an interplay of microscopic speed limits and local equilibration physics. In chapter 3, we analytically compute the electrical resistance in a special three dimensional system of gauge fields and matter. We are able to do the computation at arbitrary values of the coupling constant and frequency of the external driving electric field, albeit in the largeN limit. In chapter 4, we analyze the breakdown of the WiedemannFranz law at strong coupling and analyze various kinematic scenarios. We show that the Wiedemann Franz ratio should become extremely small if the momentum is approximately conserved (and there is no particlehole symmetry). In chapter 5, we use the memorymatrix formalism to compute the contribution of weak random fields to the transport near the Isingnematic quantum critical point. In chapter 6, we generalize our scope slightly to the general problem of computing timedependent quantities in quantum systems and present a new stateoftheart matrix product algorithm that allows us to numerically compute expectation values of observables at larger values of time than previously possible.
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Online 52. Xray studies of magnetism in the 3d transition metals [electronic resource] : from the nanoscale to the ultrafast to the nonlinear limit [2017]
 Chen, Zhao.
 2017.
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Resonant XRay phenomena associated with electronic coretovalence transitions have provided a wealth of information on modern magnetic nanostructures. In this thesis, we will describe two sets of experiments, both focusing on a different measurement related to the magnetic properties of the 3d transition metals, and both showcasing different advantages of modern XRay sources. We will show how large polarizationdependent resonant effects allow the determination of weak elementspecific static and transient magnetic moments and also offer the capability of recording movies of nanoscale magnetization dynamics with femtosecond temporal resolution. We demonstrate such effects with sensitive spectroscopic measurements of magnetism in Co/Cu alloys and of spin injection studies in Cu. In the next set of experiments, we show that when such techniques are extended to higher intensities at XRay free electron lasers, they also reveal completely new nonlinear effects, which are especially pronounced when probing spindependent effects. We will demonstrate how these nonlinear effects dramatically alter both magnetic diffraction and elastic transmission through a magneticallypatterned solid Co sample. Together, these studies show both the exceptional current capabilities of XRay in studies of 3d magnetism, but also the potential for studying interesting nonlinear phenomena in solids as brighter XRay sources become available in the future.
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Online 53. Argus [electronic resource] : a 16pixel millimeterwave spectrometer [2016]
 Sieth, Matthew Michael.
 2016.
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This thesis presents the development and deployment of Argus, a 16pixel millimeterwave spectrometer for the 100 m Robert C. Byrd Green Bank Telescope (GBT). Argus enables astronomical imaging at stateoftheart mapping speeds and high angular resolution over the 76116 GHz band. Its applications include studies of star formation, comets, astrobiology, and astrochemistry. Argus was installed on the GBT and measured rst light in March 2016. It will be available to the general radio astronomy community beginning in the winter 2016 observing semester. This work has demonstrated a novel scalable approach to building a focal plane array. The Argus array is built in 4pixel subunits, which are tiled together to form the 16pixel array. In principle, these subunits could be used as the building blocks of an even larger array. Every part is designed to be compact, massproducible, and as economical as possible. The core technology is based on miniaturized receiver modules, which integrate lownoise ampli ers, a bandpass lter, and a mixer into a single compact unit that would be amenable to automated assembly. The Argus receiver array achieved low noise performance over a very wide bandwidth, which both enables a number of new scienti c opportunities in the near term while demonstrating the viability of the design concept for future receiver designs.
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Online 54. Aspects of ChernSimonsmatter theories [electronic resource] [2016]
 Radic̆ević, Dorde.
 2016.
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This thesis studies several facets of ChernSimonsmatter theories, threedimensional systems of great interest to many physicists. The first of these three topics deals with theories in which matter is in the bifundamental representation of the ChernSimons gauge group, as these are the natural candidates for describing higherspin deviations from Einstein gravity. The second subject is the physics of theories with nonunitary matter, as these (in turn) are natural descriptions of fourdimensional Einstein gravity in de Sitter space. Finally, the third topic covered concerns the nature of monopoles in these theories, and includes a novel computation of scaling dimensions of simple monopole operators in conformal ChernSimonsfermion theories.
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Online 55. Aspects of strongly interacting quantum systems without translational symmetry [electronic resource] [2016]
 Ramirez, David M.
 2016.
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In this thesis, we study the emergence and dynamics of strongly interacting quantum field theories in a variety of spacetime dimensions, primarily using the holographic duality. We use the duality to probe the low energy dynamics, thermodynamics, and transport properties of such systems, with an emphasis on understanding the implications of translational symmetry breaking. After illustrating the emergence of strong dynamics in a concrete and phenomenologically motivated example, we utilize the duality to study the structure of low energy excitations in holographic systems, in particular finding instances where the low energy spectral weight has nontrivial momentum space structure. With the inclusion of translational symmetry breaking, we find explicit examples where conjectured bounds on the ratio shear viscosity to entropy density are parametrically violated, as well as evidence for new disordered strongly interacting quantum critical points with nontrivial, disorder dependent critical exponents and exotic transport behavior.
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Online 56. Ballistic conduction in graphene heterostructures [electronic resource] [2016]
 Lee, Menyoung.
 2016.
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Electronic transport in a solid is ballistic unless disturbed by disorder. This work describes experiments on a twodimensional electron system that resides in the heterostructure formed by graphene and hexagonal boron nitride. The ballistic conduction of electrons is probed across micron length scales by examining the transverse electron focusing effect, in which semiclassical electron trajectories emanating from a point on the system boundary are bent by an applied magnetic field and are focused onto another point. Internal reflection at the boundary extends these trajectories into skipping orbits; the observation and analysis of ballistic conduction that proceeds thus characterizes the interaction of an electron in graphene with the edge. Transverse electron focusing is also exhibited in the 14 nmperiod moire superlattice, which is formed by the incommensurability and misalignment between the graphene and boron nitride lattices. At low temperatures, ballistic motion exhibits caustics of skipping orbits extending over hundreds of superlattice periods, reversals of the cyclotron revolution for five successive minibands, and breakdown of cyclotron orbits near van Hove singularities. A theory of nearly free Dirac fermions that obey semiclassical equations of motion successfully describes the system. The interlayer interaction parameter and the full miniband structure can be determined quantitatively. Probing such miniband conduction properties is a necessity for engineering novel transport behaviors in superlattices, and the results suggest possibilities for new device functions and more exotic physics in similar van der Waals heterostructures. A direct pointtopoint measurement of ballistic transport also enables quantitative measurement of the effect of the electronelectron interaction on the transport of quasiparticles in a clean twodimensional Fermi liquid, in particular the crossover from the regime of ballistic transport to the viscous and hydrodynamic flow regime as a function of increasing temperature.
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Online 57. Coherent LQG control, freecarrier oscillations, optical ising machines and pulsed OPO dynamics [electronic resource] [2016]
 Hamerly, Ryan Michael.
 2016.
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Broadly speaking, this thesis is about nonlinear optics, quantum mechanics, and computing. More specifically, it covers four topics: Coherent LQG Control, FreeCarrier Oscillations, Optical Ising Machines and Pulsed OPO Dynamics. Tying them all together is a theory of open quantum systems called the SLH model, which I introduce in Chapters 12. The SLH model is a general framework for open quantum systems that interact through bosonic fields, and is the basis for the quantum circuit theory developed in the text. Coherent LQG control is discussed in Chapters 34, where I demonstrate that coherent feedback outperforms measurementbased feedback for certain linear quadraticGaussian (LQG) problems, and explain the discrepancy by the former's simultaneous utilization of both light quadratures. Semiclassical truncatedWigner techniques for quantumoptical networks are discussed in Chapter 5, leading to a thorough discussion of quantum noise in systems with freecarrier nonlinearities (Chapter 6), comparison to the Kerr nonlinearity, and potential applications for analog computing based on limit cycles and amplification (Chapters 78). Ising machines based on optical parametric oscillators (OPOs) are discussed in Chapters 910, the former focusing on large 1D and 2D networks of OPOs, and the latter on the dynamics of a single OPO in the ultrafast, synchronouslypumped regime. Optical properties and design considerations for silicon photonic waveguides are are treated in Chapter 11.
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Online 58. Datadriven methods for modeling of extreme events [electronic resource] [2016]
 Shenoy, Saahil.
 2016.
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The motivation of this thesis is to model the risk of extreme events. With rapidly increasing amounts of available data, the statistics on extreme events is more accurate. The developed methodology in this thesis work extends existing actuarial science and financial risk approaches. These approaches use a branch of statistics known as extreme value theory (EVT). One of the extensions is analyzing risk trends across years for each calendar month. This is a highly nontrivial problem because extreme events might not happen every year for a given month. A Bayesian maximum a posteriori (MAP) formulation is applied to tackle this problem. One of the main applications of this novel method is characterizing the risk trends of 100 year extreme high temperature events. We focus on these extreme weather events since their occurrences are immensely disruptive and damaging. The nontriviality of the problem is in distinguishing climate change from the immense variations in weather, both spatially and temporally. The data analyzed is from the continental U.S. from 1979 to 2015. We show that aggregation from multiple locations is valid in order to get more accurate statistics on 100 year extremes. There is a factor of 2.7 relative increase for 100year extreme high temperature event risk that is found in the last 4 decades of the climate data. This is primarily caused by both a factor 2.3 relative increase in the number of and a 41\% increase in magnitude of extreme high temperature events over the last 37 years. Another method is also developed for building a nonparametric stochastic model of the distribution from large data sets. This is done with an modified version of quantile regression (QR). This new QR formulation also tackles two major issues with the original QR method itself. In the second main application example, we consider probabilistic forecasting of the loads in electrical power grid. A probabilistic forecast is given by our estimated QR model. The probabilistic evaluation of risk is important because load volatility is increasing with the ongoing proliferation of the renewable generation. The most important risk factor is that the required amount of the electricity cannot be procured at the spot market, because the standby generation capacity is insufficient. An application to electric utility data shows significant improvement in load balancing risk compared to existing methods.
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Online 59. Demonstration of the hollow channel plasma wakefield accelerator [electronic resource] [2016]
 Gessner, Spencer J.
 2016.
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A plasma wakefield accelerator is a device that converts the energy of a relativistic particle beam into a largeamplitude wave in a plasma. The plasma wave, or wakefield, supports an enormous electric field that is used to accelerate a trailing particle beam. The plasma wakefield accelerator can therefore be used as a transformer, transferring energy from a highcharge, lowenergy particle beam into a highenergy, lowcharge particle beam. This technique may lead to a new generation of ultracompact, highenergy particle accelerators. The past decade has seen enormous progress in the field of plasma wakefield acceleration with experimental demonstrations of the acceleration of electron beams by several gigaelectronvolts. The acceleration of positron beams in plasma is more challenging, but also necessary for the creation of a highenergy electronpositron collider. Part of the challenge is that the plasma responds asymmetrically to electrons and positrons, leading to increased disruption of the positron beam. One solution to this problem, first proposed over twenty years ago, is to use a hollow channel plasma which symmetrizes the response of the plasma to beams of positive and negative charge, making it possible to accelerate positrons in plasma without disruption. In this thesis, we describe the theory relevant to our experiment and derive new results when needed. We discuss the development and implementation of special optical devices used to create long plasma channels. We demonstrate for the first time the generation of meterscale plasma channels and the acceleration of positron beams therein.
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Online 60. Discovering the QCD axion with black holes and gravitational waves [electronic resource] [2016]
 Huang, Xinlu.
 2016.
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Advanced LIGO is the first experiment to detect gravitational waves. Through su perradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant above the GUT scale. When an axion's Comp ton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a "gravitational atom." Through the superradiance process, the number of axions occupying the bound levels grows exponentially, extracting energy and angular momentum from the black hole. Axions transitioning between levels of the gravitational atom and axions annihilating to gravitons can produce observable gravitational wave signals. The signals are longlasting, monochromatic, and can be distinguished from ordinary astrophysical sources. We estimate up to O(1) transition events at aLIGO for an axion between 10^−11 and 10^−10 eV and up to 10^4 annihila tion events for an axion between 10^−13 and 10^−11 eV. In the event of a null search, aLIGO can constrain the axion mass for a range of rapidly spinning black hole formation rates. Axion annihilations are also promising for much lighter masses at future lowerfrequency gravitational wave observatories; the rates have large uncertainties, dominated by supermassive black hole spin distributions. Our projections for aLIGO are robust against perturbations from the black hole environment and account for our updated exclusion on the QCD axion of 6 × 10^−13 eV < μa < 2 × 10^−11 eV suggested by stellar black hole spin measurements.
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Online 61. An effective field theory approach to cosmological structure formation [electronic resource] [2016]
 Foreman, Simon.
 2016.
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One of the main frontiers of observational cosmology is to map out how matter is distributed throughout the universe. The clustering patterns of galaxies and other astrophysical objects contain imprints of the universe's expansion history, the properties of the quantum fluctuations that are believed to have seeded the latetime structures we observe, and possibly other new and exotic physical processes. To extract this information from observations, we require a robust theoretical framework for how gravitational clustering works at large distances. This dissertation presents such a framework, which adapts the ideas of "effective field theory" (originally developed in the context of particle physics and quantum fields) to describe how small perturbations in an initially homogeneous distribution of matter evolve through cosmic time. In this framework, the perturbations are described as an effective fluid at long distances, with a stress tensor that parametrizes the effects of shortwavelength processes on the longdistance dynamics of the fluid. This stress tensor can be written as an expansion in longwavelength fields (such as the matter overdensity) and spatial derivatives, and the coefficients of this expansion can be matched either to observations or to numerical simulations of gravitational clustering. Through several explicit calculations of correlation functions (particularly the power spectrum) of the cosmic density field, I demonstrate how the presence of this stress tensor renders the theory free of many of the issues that have plagued other perturbative approaches to gravitational clustering. I also perform several comparisons of the theory's predictions to measurements from dark matteronly Nbody simulations, demonstrating the theory's ability to reproduce these measurements at over a wider range of scales and at higher precision than previously possible. The results in this dissertation represent significant advances in our understanding of cosmological perturbation theory, and their eventual application to observations of largescale structure will likely be a great help in furthering our knowledge about the universe we inhabit.
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Online 62. The effective field theory of largescale structure in cosmology [electronic resource] [2016]
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So far, the cosmic microwave background has provided most of the significant constraints on cosmological parameters, but because of Silk damping and foreground contamination, the Planck Satellite has essentially reached the limit in constraining nonGaussianity in scalar modes with the cosmic microwave background. Fortunately, the distribution of galaxies today is correlated with the conditions present in the early universe, so largescale structure surveys can help us understand the early universe by observing the currentday galaxy distribution. In this way, it is likely that the next leading source of cosmological information will come from largescale structure surveys like LSST and Euclid. In order for largescale structure to significantly improve our knowledge of the early universe, for example by constraining f_NL < 1 through bispectrum measurements, the largescale structure observables must be understood to percent level, even in the quasilinear regime of structure formation. Recently, a research program called the Effective Field Theory of LargeScale Structure was launched with this purpose. In this thesis, I will develop two pieces of that program: the effective field theory in redshift space, and the description of baryonic effects in the effective field theory. Finally, I will present work which computes the first slowroll corrections to the volume of the universe and the universal entropy bound for slowroll eternal inflation.
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Online 63. Electrical, mechanical, and optical characterization of twodimensional materials with molecular overlayers [electronic resource] [2016]
 Gallagher, Patrick.
 2016.
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A twodimensional object is entirely surface, with no interior. Its immediate surroundings will accordingly influence its response to electrical, mechanical, and optical stimuli. This thesis explores two different twodimensional electron systems with molecular overlayers: the surface electron liquid in strontium titanate induced by electrolyte gating, and graphene decorated by ordered adsorbates. Strontium titanate is a band insulator that goes superconducting when doped with remarkably few electrons. By accumulating positive ions at a strontium titanate surface, the electrolyte gating technique can create a twodimensional electron system with gatetunable superconductivity. I combine an electrolyte gate with nanopatterned metaloxide gates to realize the first gatetunable superconducting weak link in this promising correlated electron system. With the same technique I create a ballistic onedimensional channel in strontium titanate, and use this channel to perform inplane tunneling spectroscopy of the superconducting state. Finally, using strontium titanate as a test case, I describe a method to improve mobility of generic electrolytegated surface systems by protecting the channel with a thin layer of hexagonal boron nitride. In the second part of this thesis, I use highresolution atomic force microscopy to reveal a nanotexture that unexpectedly forms on flakes of graphene (and boron nitride) prepared in laboratory air: a "superlattice" of topographic stripes whose period is 4 nm. I argue that these stripes are selfassembled environmental adsorbates, and show that they are responsible for graphene's strongly anisotropic frictiona property previously believed to result from periodic rippling of the graphene sheet itself. In agreement with this selfassembly picture, I demonstrate that the local axis of high friction can be patterned with submicron precision by appropriate mechanical contact. I further show that the stripes produce anisotropic optical response, and I discuss the potential influence of the stripesuperlattice on graphene's electronic properties.
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3781 2016 G  Inlibrary use 
 Yuan, Hongyuan.
 2016.
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Thermionic energy converters (TECs) are a direct heattoelectricity conversion technology with the potential to outperform the current stateoftheart solidstate energy conversion technologies in a wide range of working temperatures. TECs could not only be applied to largescale power plants in a tandem cycle, but could also be deployed in distributed power generation systems at small scales. In a TEC, electrons evaporate from a hot electrode (the cathode) into a vacuum gap and are collected by a cooler electrode (the anode) to generate electric energy. However, the published TECs suffer from low output voltage as well as low output current because the work function of the anode is too high and the space charge barrier in the interelectrode is too strong, which ultimately lead to low conversion efficiency. In this thesis, I will first present a phenomenological model to calculate a material's work function. This model shows that graphene has great potential to yield an ultralow work function. I will then experimentally demonstrate such a graphene anode in an ultrahigh vacuum system. The graphene is grown on a piece of copper foil by chemical vapor deposition. It is then transferred onto a 20 nm thick HfO2 layer prepared by atomic layer deposition on silicon. After insitu deposition of a monolayer of Cs/O, the work function of the graphene anode is dramatically reduced from 4.62 eV to 1.25 eV. Furthermore, I will show that electrostatic gating graphene through the HfO¬2 dielectric layer can further reduce the work function of graphene. Due to the absence of surface Fermi level pinning and low surface state density according to graphene's linear dispersion relation, the Fermi level of graphene can by effectively raised through a DC bias with negligible energy consumption. I will show that combining Cs/O surface coating and electrostatic gating would lead to a worldrecord low work function for graphene of 1.0 eV. Finally, I will demonstrate a TEC prototype based on this graphene anode, together with a commercial dispenser cathode. At the cathode working temperature of 1000 ˚C, the work functions of both of the electrodes are reduced by Ba. In addition, this TEC prototype deploys a nanomanipulator system that can reduce the interelectrode gap to 17 μm, leading to a much reduced space charge barrier. By addressing the two challenges simultaneously, a low work function anode and minimizing the space charge barrier, the overall conversion efficiency of this TEC prototype is improved by a factor of over 50, with an estimated maximum electronic conversion efficiency of 9.8 %, which is the highest reported by far at this relatively low working temperature.
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 Stanford University. Department of Physics (Sponsor)
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Preference to freshmen. The course will begin with a description of the current standard models of gravitation, cosmology, and elementary particle physics. We will then focus on frontiers of current understanding including investigations of very early universe cosmology, string theory, and the physics of black holes.
Preference to freshmen. The course will begin with a description of the current standard models of gravitation, cosmology, and elementary particle physics. We will then focus on frontiers of current understanding including investigations of very early universe cosmology, string theory, and the physics of black holes.  Collection
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Online 66. F16PHYSICS2101 : Mechanics, Fluids, and Heat. 2016 Fall [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
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How are the motions of objects and the behavior of fluids and gases determined by the laws of physics? Students learn to describe the motion of objects (kinematics) and understand why objects move as they do (dynamics). Emphasis on how Newton's three laws of motion are applied to solids, liquids, and gases to describe phenomena as diverse as spinning gymnasts, blood flow, and sound waves. Understanding manyparticle systems requires connecting macroscopic properties (e.g., temperature and pressure) to microscopic dynamics (collisions of particles). Laws of thermodynamics provide understanding of realworld phenomena such as energy conversion and performance limits of heat engines. Everyday examples are analyzed using tools of algebra and trigonometry. Problemsolving skills are developed, including verifying that derived results satisfy criteria for correctness, such as dimensional consistency and expected behavior in limiting cases. Physical understanding fostered by peer interaction and demonstrations in lecture, and interactive group problem solving in discussion sections. Prerequisite: high school algebra and trigonometry; calculus not required.
How are the motions of objects and the behavior of fluids and gases determined by the laws of physics? Students learn to describe the motion of objects (kinematics) and understand why objects move as they do (dynamics). Emphasis on how Newton's three laws of motion are applied to solids, liquids, and gases to describe phenomena as diverse as spinning gymnasts, blood flow, and sound waves. Understanding manyparticle systems requires connecting macroscopic properties (e.g., temperature and pressure) to microscopic dynamics (collisions of particles). Laws of thermodynamics provide understanding of realworld phenomena such as energy conversion and performance limits of heat engines. Everyday examples are analyzed using tools of algebra and trigonometry. Problemsolving skills are developed, including verifying that derived results satisfy criteria for correctness, such as dimensional consistency and expected behavior in limiting cases. Physical understanding fostered by peer interaction and demonstrations in lecture, and interactive group problem solving in discussion sections. Prerequisite: high school algebra and trigonometry; calculus not required.  Collection
 Stanford University Syllabi
Online 67. F16PHYSICS2201 : Mechanics, Fluids, and Heat Laboratory. 2016 Fall [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
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Guided handson exploration of concepts in classical mechanics, fluids, and thermodynamics with an emphasis on student predictions, observations and explanations. Pre or corequisite: PHYSICS 21.
Guided handson exploration of concepts in classical mechanics, fluids, and thermodynamics with an emphasis on student predictions, observations and explanations. Pre or corequisite: PHYSICS 21.  Collection
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Online 68. F16PHYSICS6101 : Mechanics and Special Relativity. 2016 Fall [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
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(First in a threepart advanced freshman physics series: PHYSICS 61, PHYSICS 63, PHYSICS 65.) This course covers Einstein's special theory of relativity and Newtonian mechanics at a level appropriate for students with a strong high school mathematics and physics background, who are contemplating a major in Physics or Engineering Physics, or are interested in a rigorous treatment of physics. Postulates of special relativity, simultaneity, time dilation, length contraction, the Lorentz transformation, causality, and relativistic mechanics. Central forces, contact forces, linear restoring forces. Momentum transport, work, energy, collisions. Angular momentum, torque, moment of inertia in three dimensions. Damped and forced harmonic oscillators. Uses the language of vectors and multivariable calculus. Recommended prerequisites: Mastery of mechanics at the level of AP Physics C and AP Calculus BC or equivalent. Corequisite: MATH 51.
(First in a threepart advanced freshman physics series: PHYSICS 61, PHYSICS 63, PHYSICS 65.) This course covers Einstein's special theory of relativity and Newtonian mechanics at a level appropriate for students with a strong high school mathematics and physics background, who are contemplating a major in Physics or Engineering Physics, or are interested in a rigorous treatment of physics. Postulates of special relativity, simultaneity, time dilation, length contraction, the Lorentz transformation, causality, and relativistic mechanics. Central forces, contact forces, linear restoring forces. Momentum transport, work, energy, collisions. Angular momentum, torque, moment of inertia in three dimensions. Damped and forced harmonic oscillators. Uses the language of vectors and multivariable calculus. Recommended prerequisites: Mastery of mechanics at the level of AP Physics C and AP Calculus BC or equivalent. Corequisite: MATH 51.  Collection
 Stanford University Syllabi
Online 69. F16PHYSICS6102 : Mechanics and Special Relativity. 2016 Fall [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

(First in a threepart advanced freshman physics series: PHYSICS 61, PHYSICS 63, PHYSICS 65.) This course covers Einstein's special theory of relativity and Newtonian mechanics at a level appropriate for students with a strong high school mathematics and physics background, who are contemplating a major in Physics or Engineering Physics, or are interested in a rigorous treatment of physics. Postulates of special relativity, simultaneity, time dilation, length contraction, the Lorentz transformation, causality, and relativistic mechanics. Central forces, contact forces, linear restoring forces. Momentum transport, work, energy, collisions. Angular momentum, torque, moment of inertia in three dimensions. Damped and forced harmonic oscillators. Uses the language of vectors and multivariable calculus. Recommended prerequisites: Mastery of mechanics at the level of AP Physics C and AP Calculus BC or equivalent. Corequisite: MATH 51.
(First in a threepart advanced freshman physics series: PHYSICS 61, PHYSICS 63, PHYSICS 65.) This course covers Einstein's special theory of relativity and Newtonian mechanics at a level appropriate for students with a strong high school mathematics and physics background, who are contemplating a major in Physics or Engineering Physics, or are interested in a rigorous treatment of physics. Postulates of special relativity, simultaneity, time dilation, length contraction, the Lorentz transformation, causality, and relativistic mechanics. Central forces, contact forces, linear restoring forces. Momentum transport, work, energy, collisions. Angular momentum, torque, moment of inertia in three dimensions. Damped and forced harmonic oscillators. Uses the language of vectors and multivariable calculus. Recommended prerequisites: Mastery of mechanics at the level of AP Physics C and AP Calculus BC or equivalent. Corequisite: MATH 51.  Collection
 Stanford University Syllabi
Online 70. Globalmode helioseismology [electronic resource] : extensions of a wellused method [2016]
 Larson, Tim.
 2016.
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Globalmode helioseismology has been used extensively to precisely infer the detailed properties of the solar interior. Multiple algorithms have been applied to several different datasets, which now span over two solar cycles. This dissertation deals primarily with two instruments, namely the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory, and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory. For MDI, we have two velocity datasets spanning the 15 years from 1996 to 2011: highresolution images which were taken for a few months each year, and lowresolution images which were taken almost all the time. For HMI, we have even higher resolution velocity images taken since 2010. Unlike MDI, HMI also provides intensity data. The initial motivation for this study was to address known systematic errors in the analysis of MDI data, as well as discrepancies with inferences drawn by other projects, most notably the Global Oscillation Network Group. In particular, the MDI results indicated a highlatitude peak in the solar rotation rate, which is now believed to be spurious. Also, certain fits resulted in normalized residuals that indicate the fit is not using the correct model. Lastly, MDI saw an annual periodicity in frequency shifts, which can only be because of errors in geometry. Now that MDI is no longer operating, it has also become important to achieve continuity between the MDI and HMI datasets. To that end, both have been processed in their entirety using the same set of software. Since the original software was written when computational capabilities were far less than now, this involved the application of several updates. At the same time, we have adopted better models of the physics behind the oscillations and applied various geometric corrections. In this dissertation we investigate how these changes affected the globalmode parameters from the MDI analysis and the systematic errors therein. We then apply the fully updated analysis to the HMI data, and make a comparison of mode parameters derived from the various datasets from the two instruments. We find methods that decrease or eliminate the systematic errors mentioned above. Hence, inferences of the Sun's interior rotation have become more robust. Further, the comparison between MDI and HMI encourages the concatenation of their datasets, which may allow for the detection of new oscillation modes.
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Online 71. Imaging current in materials [electronic resource] [2016]
 Spanton, Eric M.
 2016.
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Scanning superconducting quantum interference device (SQUID) microscopy is an incredibly sensitive way to image magnetic fields. One application of this technique is to spatially map magnetic fields which originate from moving electrons (i.e. electrical current), and interpret the pattern of current in order to learn more about how electrons behave in interesting materials. In lanthanum aluminatestrontium titanate, two insulators which can host a twodimensional conducting state at their interface, we discovered locally enhanced conduction due to domain structure in the strontium titanate. 2D topological insulators are a class of materials which are predicted to host special conducting states along the edges of patterned devices, and we were able to image current along the edges of devices in two such materials: HgTe quantum wells and InAs/GaSb quantum wells. In InAs/GaSb, we found that backscattering in the edges was temperature independent and elucidated the presence of edge states in socalled 'trivial' regimes. These results call into question the prevailing interpretation of edge states in InAs/GaSb as topological, and conclude that better experimental evidence is required to definitively identify a 2D topologically insulating state in this material. Finally, we've investigated a fundamental property of Josephson junctions called the currentphase relation in fewmode InAs nanowire junctions. InAs nanowires which are in close contact with conventional superconductors are of great interest due to the possible realization of exotic particles called Majorana quasiparicles which may be of use for quantum computation. We've probed the disorder associated with adding superconductivity to nanowires by measuring the shape of the currentphase relation and finding that it fluctuates as a function of electron density and from junction to junction.
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Online 72. Investigating the quantum properties of jets and the search for a supersymmetric top quark partner with the ATLAS detector [electronic resource] [2016]
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Quarks and gluons are the fundamental building blocks of matter responsible for most of the visible energy density in the universe. However, they cannot be directly observed due to the confining nature of the strong force. The Large Hadron Collider (LHC) uses protonproton collisions to probe the highest energy reactions involving quarks and gluons happening at the smallest distance scales ever studied in a terrestrial laboratory. The observable consequence of quark and gluon production in these reactions is the emergent phenomenon known as the jet: a collimated stream of particles traveling at nearly the speed of light. The quantum properties of the initiating quarks and gluons are encoded in the distribution of energy inside and around jets. These quantum properties of jets can be used to study the high energy nature of the strong force and provide a way to tag the hadronic decays of heavy boosted particles. The ATLAS detector at the LHC is wellsuited to perform measurements of the internal structure of high energy jets. A variety of novel techniques utilizing the unique capabilities of the ATLAS calorimeter and tracking detectors are introduced in order to probe the experimental and theoretical limits of the quantum properties of jets. Studying quarks and gluons may also be the key to understanding the fundamental problems with the Standard Model (SM) of particle physics. In particular, the top quark has a unique relationship with the newly discovered Higgs boson and as such could be a portal to discovering new particles and new forces. In many extensions of the SM, the top quark has a partner with similar relationships to other SM particles. For example, a scalar top partner (stop) in Supersymmetry (SUSY) could solve the Higgs boson mass hierarchy problem. Miraculously, a SUSY neutralino could also account for the dark matter observed in the universe and may be copiously produced in stop decays. Highenergy top quarks from stop decays result in jets with a rich structure that can be identified using the techniques developed in the study of the quantum properties of jets. While there is no significant evidence for stop production at the LHC, the stringent limits established by this search have important implications for SUSY and other models.
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Online 73. Modeling the distribution of dark matter and its connection to galaxies [electronic resource] [2016]
 Mao, YaoYuan.
 2016.
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Despite the mysterious nature of dark matter and dark energy, the LambdaCold Dark Matter (LCDM) model provides a reasonably accurate description of the evolution of the cosmos and the distribution of galaxies. Today, we are set to tackle more specific and quantitative questions about the galaxy formation physics, the nature of dark matter, and the connection between the dark and the visible components. The answers to these questions are however elusive, because dark matter is not directly observable, and various unknowns lie between what we can observe and what we can calculate. Hence, mathematical models that bridge the observable and the calculable are essential for the study of modern cosmology. The aim of my thesis work is to improve existing models and also to construct new models for various aspects of the dark matter distribution, as dark matter structures the cosmic web and forms the nests of visible galaxies. Utilizing a series of cosmological dark matter simulations which span a wide dynamical range and a statistical sample of zoomin simulations which focus on individual dark matter halos, we develop models for the spatial and velocity distribution of dark matter particles, the abundance of dark substructures, and the empirical connection between dark matter and galaxies. As more precise observational results become available, more accurate models are then required to test the consistency between these results and the LCDM predictions. For all the models we investigate, we find that the formation history of dark matter halos always plays a crucial role. Neglecting the halo formation history would result in systematic biases when we interpret various observational results, including dark matter direct detection experiments, the detection of dark substructures with stronglensed systems, the largescale spatial clustering of galaxies, and the abundance of dwarf galaxies. Rectifying this, our work will enable us to fully utilize the complementary power of diverse observational datasets to test the LCDM model and to seek new physics.
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Online 74. Moonshine and SW(3/2, 2) [electronic resource] [2016]
 Whalen, Daniel.
 2016.
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Superstring compactification on a manifold of Spin(7) holonomy gives rise to a 2d worldsheet conformal field theory with an extended supersymmetry algebra. Such manifolds have a c=12 realization of the symmetry group SW(3/2, 2). In this thesis, I explore the characters of this algebra, and decompose the elliptic genus of a general Spin(7) compactification in terms of these characters, giving results that are suggestive of a large symmetry group. I make this suggestion manifest by constructing a SCFT that permits an M24, Co2 and Co3, and which has an action by the SW(3/2, 2) algebra.
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Online 75. New experimental tests for gravity and dark matter [electronic resource] [2016]
 Wiser, Timothy D.
 2016.
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 Book — 1 online resource.
 Summary

The behavior of gravity is well understood and highly constrained on length scales from millimeters to the size of the Solar System. New physics, such as extra dimensions or new forces, may modify the behavior of gravity below a millimeter. On the other end of the spectrum, observations of galaxies, galaxy clusters, supernovae, and the Cosmic Microwave Background all point to the gravitational dominance of dark matter and dark energy over the ordinary matter content of the Universe. It is therefore worth investigating, with high precision, the behavior of gravity at the longest distance scales as well. In this dissertation, I describe a recent proposal for a spacebased experiment, optimized to test the inverse square law with great accuracy at scales of up to 100 AU. This is the largest length scale that can be reached with a direct probe using current technology. I also describe a new experimental strategy for testing putative signals of dark matter decay or annihilation. Merging galaxy clusters such as the Bullet Cluster provide a powerful testing ground for indirect detection of dark matter. The spatial distribution of the dark matter is both directly measurable through gravitational lensing and substantially different from the distribution of potential astrophysical backgrounds. I propose to use this spatial information to identify the origin of indirect detection signals, and show that even statistical excesses of a few sigma can be robustly tested for consistencyor inconsistencywith a dark matter source.
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Online 76. New insights into galaxy cluster astrophysics using the Suzaku Xray satellite [electronic resource] [2016]
 Urban, Ondrej.
 2016.
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 Book — 1 online resource.
 Summary

Galaxy clusters enable a broad range of astrophysical studies, from the microphysics of hot tenuous plasmas, to the physics of galaxy evolution, to constraining cosmological models. In particular, much can, and has, been learned from detailed studies of the nearest brightest systems, in which the relevant astrophysics can be viewed "in closeup". The focus of this thesis is the analysis of , and extraction of novel results from, observations of nearby galaxy clusters made with the Suzaku Xray satellite. In particular, the first part of the thesis is focused on the analysis of data from Suzaku Key Project observations of the Perseus Cluster, the Xray brightest cluster in the sky, which offered the most complete view to date of any galaxy cluster from its core to the outer edge. The results are presented across several chapters. In Chapter 2, we examine the behaviour of various physical properties of the intracluster medium (ICM), some of which, most prominently including the entropy, indicate a presence of density inhomogeneities at large radii (r> r500). In Chapter 3, we report evidence for large megaparsecscale sloshing motions of the ICM in Perseus, a phenomenon which had not been observed before at these scales. In Chapter 4, we present the first spatially resolved study of the chemical composition of the ICM throughout the full volume of a cluster. Notably, we find a homogeneous distribution of heavy elements at large radii which indicates that these elements, produced by supernovae, were likely injected into and mixed with the intergalactic gas before galaxy clusters formed. In the second part of this thesis, I present a detailed spectral examination of Suzaku observations of the four Xray brightest clusters, in order to search for the presence of a ~3.5 keV Xray emission line. The presence of such a line has been claimed in some previous Xray studies of the Perseus Cluster, and some other galaxies and clusters. It has been proposed that such a feature could be a decay signature from sterile neutrino dark matter. My results present a severe challenge to this interpretation. Alternative scenarios for the origin of the ~3.5 keV feature are discussed.
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Online 77. New techniques for precision atom interferometry and applications to fundamental tests of gravity and of quantum mechanics [electronic resource] [2016]
 Kovachy, Tim.
 2016.
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 Book — 1 online resource.
 Summary

Lightpulse atom interferometryin which quantum mechanical atomic wave packets are split along two paths and later recombined and made to interfere by sequences of optical pulsesis a remarkably sensitive technique for measuring inertial forces, allowing it to be a valuable tool for applications ranging from fundamental tests of gravity to geodesy and inertial navigation. The inertial sensitivity of an atom interferometer is proportional to its enclosed spacetime areathat is, the product of the spatial separation between the two interferometer paths and the interferometer duration. Therefore, new techniques that allow this spacetime area to be increased are essential in order for atom interferometry to reach its full potential. In this thesis, I describe the development of such techniques. We approach the problem of increasing the interferometer spacetime area on two fronts. First, we implement new methods to increase the momentum transferred by the beam splitters of the interferometer. The velocity difference and therefore the spatial separation of the interferometer paths are proportional to this momentum transfer. Conventional atom optics techniques involve beam splitters that transfer two photon momentum recoils (2 hbar k) to the atoms. I will discuss our realization of large momentum transfer (LMT) beam splitters that transfer up to 100 hbar k. Second, we have built a 10 m tall atomic fountain that allows the total interferometer duration to be increased to 2 s. Ultimately, we combined LMT atom optics with longduration atom interferometry in the 10 m atomic fountain, leading to very large spacetime area atom interferometers. In these very large area atom interferometers, the separation between the two atomic wave packets that respectively travel along the two interferometer paths reaches distances of up to 54 cm. Therefore, in addition to offering greatly increased inertial sensitivity, these interferometers probe the quantum mechanical wavelike nature of matter in a new macroscopic regime. I will discuss the techniques we devised to overcome the many technical challenges associated with such interferometers, which in other apparatus have prevented interference from being maintained for path separations larger than 1 cm. I will also describe initial results from the use of our very large area interferometers to test the equivalence principle with Rb85 and Rb87 and our plans for further progress in this direction. Very large area atom interferometry requires high laser power and extremely cold atom sources. We have developed a novel high power, frequency doubled laser source at 780 nm that is suitable for atom optics. Also, we have implemented a sequence of matter wave lenses to prepare and measure atomic ensembles with recordlow effective temperatures of 50 pK. In addition to applications in atom interferometry, we expect that such an atom source will be broadly useful for a wide range of experiments.
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Online 78. Particle acceleration in magnetized, relativistic outflows of astrophysical sources [electronic resource] [2016]
 Yuan, Yajie.
 2016.
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 Summary

Many powerful and variable gammaray sources, including pulsar wind nebulae (particularly the Crab Nebula), active galactic nuclei and gammaray bursts, seem capable of accelerating particles to gammarayemitting energies efficiently over very short time scales. These are likely due to rapid dissipation of electromagnetic energy in a highly magnetized, relativistic plasma. We term such a process as "magnetoluminescence". One possible scenario is that in the highly magnetized outflow of the prime mover, an ideal instability causes a tangled, high energy configuration to relax to a lower energy state over light crossing time scales; during the process extended E > B or E · B ≠ 0 regions can be formed and sustained as the particles are accelerated up to the radiation reaction limit, removing the electromagnetic energy in the form of gammaray emission. In order to test this conjecture, we devise simple models of magnetized, relativistic plasma configurations, which allow us to study in detail the macroscopic instability that leads to dramatic dissipation of electromagnetic energy. One class of examples are the socalled linear forcefree equilibria within confining walls or 3D periodic boxes. Using analytical technique and MHD simulations, we find that many of the short wavelength configurations are unstable to ideal modes; the instability grows on Alfven wave crossing time scales (close to the light crossing time scale when the magnetization is high), and the system eventually relaxes to the longest wavelength state, or lowest energy state, as allowed by a conserved total helicity. We then used one of the lowest order unstable equilibria as a testbed to understand the generic features of particle acceleration and radiation in a relativistic, magnetized plasma, using radiative particleincell (PIC) simulations. We find that the ideal instability forces a dynamic current layer formation and the highest energy particles are first accelerated by the parallel electric field in the current layers; fast variability can be produced by particle bunches ejected from the current layers. Meanwhile, we have been working closely with the observations, particularly the interpretation of multiwavelength data of the inner knot in the Crab Nebula, which was suspected to be the site of the gammaray flares. Though no convincing evidence has been found in that respect, we did a careful examination of emission models at the knot, which prompts us to reconsider the main particle acceleration mechanisms responsible for most of the emission (in the Optical/UV/Xray wavebands) from the nebula. We think all the aforementioned results provide instructive steps along the way to learn about the basic properties of magnetized, relativistic plasmas and extreme particle acceleration. We also propose possible future directions in theoretical analysis, simulations, observations and laboratory astrophysics that may help us better understand these powerful engines in our universe.
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 Engelsen, Nils Johan.
 2016.
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Atomic sensors are pushing the boundaries in precision for timekeeping, magnetometry, and gravity gradiometry. Conventional atomic sensors are ultimately limited by the quantum projection noise. In this thesis, the quantum projection noise limit on sensing precision is circumvented by exploiting entanglement—quantum correlations between the atoms. Entangled states enabling 100fold measurement precision enhancement were generated using cavitybased measurements. Additionally, a new method was developed which allows entanglementenhanced metrology without detection noise beyond the quantum projection noise limit.
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Online 80. Searches for light scalar dark matter [electronic resource] [2016]
 Van Tilburg, Ken.
 2016.
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 Summary

If the dark matter is made up of a bosonic particle, it can be ultralight, with a mass potentially much below 1 eV. Moduli fields, whose values could set couplings and masses of known particles, are good candidates for such light dark matter. Their abundance in our Universe would manifest itself as tiny fractional oscillations of Standard Model parameters, such as the electron mass or the finestructure constant, in turn modulating length and time scales of atoms. Rods and clocks, used for gedanken experiments in the development of relativity theory, have since transformed into actual precision instruments. The size of acoustic resonators and the frequency of atomic transitions can now be measured to 1 part in 10^24 and 10^18, respectively, and thus constitute sensitive probes of moduli. Atomic gravitational wave detectors can have a timedomain response to modulus dark matter, and sense temporal oscillations of atomic frequencies down to 1 part in 10^25. This thesis gives an overview of the parameter space of modulus dark matter, and compares the sensitivity of various experimental proposals relative to existing constraints from searches for new forces. I will focus on two classes of experimental strategies in particular: resonantmass detectors (rods), and atomic spectroscopy and interferometry (clocks).
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Online 81. Searching for heavy photons in the HPS experiment [electronic resource] [2016]
 Uemura, Sho.
 2016.
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The Heavy Photon Search (HPS) is a new experiment at Jefferson Lab that searches for a massive U(1) vector boson (known as a heavy photon or A') in the MeVGeV mass range and coupling weakly to ordinary matter through a kinetic mixing interaction. The HPS experiment seeks to produce heavy photons by electron bremsstrahlung on a fixed target, is sensitive to heavy photon decays to electronpositron pairs, and targets the range in heavy photon mass from 20 to 600 MeV, and kinetic mixing strength epsilon^2 from 1E5 to 1E10. HPS searches for heavy photons using two signatures: a narrow mass resonance and displaced vertices. This dissertation presents the theoretical and experimental motivations for a heavy photon, the design and operation of the HPS experiment, and the displaced vertex search. The data used in this dissertation is the unblinded fraction of the 2015 HPS run, for the period of operation where the HPS silicon vertex tracker (SVT) was operated at its nominal position. This data was recorded from May 13 to May 18, 2015, at a beam energy of 1.056 GeV and a nominal beam current of 50 nA. The integrated luminosity is 119 inverse nanobarns, which is equivalent to 0.172 days of ideal running at the nominal beam current. This dissertation presents results (signal significance and upper limits) from the displaced vertex search in the mass range from 20 to 60 MeV, and kinetic mixing strength epsilon^2 from 2E8 to 1E10. This search does not have sufficient sensitivity to exclude a canonical heavy photon at any combination of mass and mixing strength. The strictest limit achieved in this analysis on the production of a particle that decays like a heavy photon is 115 times the expected production crosssection for a heavy photon. Factors limiting the sensitivity of this analysis are discussed. Projections of HPS performance with the full 2015 data set, and with planned improvements to the analysis, are presented. Comparisons are also made to earlier reach estimates.
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 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
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Designed for undergraduate physics majors but open to all students with a calculusbased physics background and some laboratory and coding experience. Students make and analyze observations using the telescopes at the Stanford Student Observatory. Topics covered include navigating the night sky, the physics of stars and galaxies, telescope instrumentation and operation, imaging and spectroscopic techniques, quantitative error analysis, and effective scientific communication. The course concludes with an independent project. Limited enrollment. Prerequisites: prior completion of Physics 40 or 60 series.
Designed for undergraduate physics majors but open to all students with a calculusbased physics background and some laboratory and coding experience. Students make and analyze observations using the telescopes at the Stanford Student Observatory. Topics covered include navigating the night sky, the physics of stars and galaxies, telescope instrumentation and operation, imaging and spectroscopic techniques, quantitative error analysis, and effective scientific communication. The course concludes with an independent project. Limited enrollment. Prerequisites: prior completion of Physics 40 or 60 series.  Collection
 Stanford University Syllabi
Online 83. Sp16PHYSICS2501 : Modern Physics. 2016 Spring [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
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 Summary

How do the discoveries since the dawn of the 20th century impact our understanding of 21stcentury physics? This course introduces the foundations of modern physics: Einstein's theory of special relativity and quantum mechanics. Combining the language of physics with tools from algebra and trigonometry, students gain insights into how the universe works on both the smallest and largest scales. Topics may include atomic, molecular, and laser physics; semiconductors; elementary particles and the fundamental forces; nuclear physics (fission, fusion, and radioactivity); astrophysics and cosmology (the contents and evolution of the universe). Emphasis on applications of modern physics in everyday life, progress made in our understanding of the universe, and open questions that are the subject of active research. Physical understanding fostered by peer interaction and demonstrations in lecture, and interactive group problem solving in discussion sections. Prerequisite: PHYSICS 23 or PHYSICS 23S.
How do the discoveries since the dawn of the 20th century impact our understanding of 21stcentury physics? This course introduces the foundations of modern physics: Einstein's theory of special relativity and quantum mechanics. Combining the language of physics with tools from algebra and trigonometry, students gain insights into how the universe works on both the smallest and largest scales. Topics may include atomic, molecular, and laser physics; semiconductors; elementary particles and the fundamental forces; nuclear physics (fission, fusion, and radioactivity); astrophysics and cosmology (the contents and evolution of the universe). Emphasis on applications of modern physics in everyday life, progress made in our understanding of the universe, and open questions that are the subject of active research. Physical understanding fostered by peer interaction and demonstrations in lecture, and interactive group problem solving in discussion sections. Prerequisite: PHYSICS 23 or PHYSICS 23S.  Collection
 Stanford University Syllabi
Online 84. Sp16PHYSICS25201 : Introduction to Particle Physics I. 2016 Spring [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

Elementary particles and the fundamental forces. Quarks and leptons. The mediators of the electromagnetic, weak and strong interactions. Interaction of particles with matter; particle acceleration, and detection techniques. Symmetries and conservation laws. Bound states. Decay rates. Cross sections. Feynman diagrams. Introduction to Feynman integrals. The Dirac equation. Feynman rules for quantum electrodynamics and for chromodynamics. Undergraduates register for PHYSICS 152. Graduate students register for PHYSICS 252. (Graduate students will be required to complete additional assignments in a format determined by the instructor.) Prerequisite: PHYSICS 130. Pre or corequisite: PHYSICS 131.
Elementary particles and the fundamental forces. Quarks and leptons. The mediators of the electromagnetic, weak and strong interactions. Interaction of particles with matter; particle acceleration, and detection techniques. Symmetries and conservation laws. Bound states. Decay rates. Cross sections. Feynman diagrams. Introduction to Feynman integrals. The Dirac equation. Feynman rules for quantum electrodynamics and for chromodynamics. Undergraduates register for PHYSICS 152. Graduate students register for PHYSICS 252. (Graduate students will be required to complete additional assignments in a format determined by the instructor.) Prerequisite: PHYSICS 130. Pre or corequisite: PHYSICS 131.  Collection
 Stanford University Syllabi
Online 85. Sp16PHYSICS2601 : Modern Physics Laboratory. 2016 Spring [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

Guided handson and simulationbased exploration of concepts in modern physics, including special relativity, quantum mechanics and nuclear physics with an emphasis on student predictions, observations and explanations. Pre or corequisite: PHYSICS 25.
Guided handson and simulationbased exploration of concepts in modern physics, including special relativity, quantum mechanics and nuclear physics with an emphasis on student predictions, observations and explanations. Pre or corequisite: PHYSICS 25.  Collection
 Stanford University Syllabi
Online 86. Sp16PHYSICS26101 : Introduction to Cosmology and Extragalactic Astrophysics. 2016 Spring [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

What do we know about the physical origins, content, and evolution of the Universe  and how do we know it? Students learn how cosmological distances and times, and the geometry and expansion of space, are described and measured. Composition of the Universe. Origin of matter and the elements. Observational evidence for dark matter and dark energy. Thermal history of the Universe, from inflation to the present. Emergence of largescale structure from quantum perturbations in the early Universe. Astrophysical tools used to learn about the Universe. Big open questions in cosmology. Undergraduates register for Physics 161. Graduates register for Physics 261. (Graduate students will be required to complete additional assignments in a format determined by the instructor.) Prerequisite: PHYSICS 121 or equivalent.
What do we know about the physical origins, content, and evolution of the Universe  and how do we know it? Students learn how cosmological distances and times, and the geometry and expansion of space, are described and measured. Composition of the Universe. Origin of matter and the elements. Observational evidence for dark matter and dark energy. Thermal history of the Universe, from inflation to the present. Emergence of largescale structure from quantum perturbations in the early Universe. Astrophysical tools used to learn about the Universe. Big open questions in cosmology. Undergraduates register for Physics 161. Graduates register for Physics 261. (Graduate students will be required to complete additional assignments in a format determined by the instructor.) Prerequisite: PHYSICS 121 or equivalent.  Collection
 Stanford University Syllabi
Online 87. Sp16PHYSICS33201 : Quantum Field Theory III. 2016 Spring [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

Theory of renormalization. The renormalization group and applications to the theory of phase transitions. Renormalization of YangMills theories. Applications of the renormalization group of quantum chromodynamics. Perturbation theory anomalies. Applications to particle phenomenology. Prerequisite: PHYSICS 331.
Theory of renormalization. The renormalization group and applications to the theory of phase transitions. Renormalization of YangMills theories. Applications of the renormalization group of quantum chromodynamics. Perturbation theory anomalies. Applications to particle phenomenology. Prerequisite: PHYSICS 331.  Collection
 Stanford University Syllabi
Online 88. Sp16PHYSICS37301 : Condensed Matter Theory II. 2016 Spring [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

Superfluidity and superconductivity. Quantum magnetism. Prerequisite: PHYSICS 372.
Superfluidity and superconductivity. Quantum magnetism. Prerequisite: PHYSICS 372.  Collection
 Stanford University Syllabi
Online 89. Sp16PHYSICS4301 : Electricity and Magnetism. 2016 Spring [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

What is electricity? What is magnetism? How are they related? How do these phenomena manifest themselves in the physical world? The theory of electricity and magnetism, as codified by Maxwell's equations, underlies much of the observable universe. Students develop both conceptual and quantitative knowledge of this theory. Topics include: electrostatics; magnetostatics; simple AC and DC circuits involving capacitors, inductors, and resistors; integral form of Maxwell's equations; electromagnetic waves. Principles illustrated in the context of modern technologies. Broader scientific questions addressed include: How do physical theories evolve? What is the interplay between basic physical theories and associated technologies? Discussions based on the language of mathematics, particularly differential and integral calculus, and vectors. Physical understanding fostered by peer interaction and demonstrations in lecture, and discussion sections based on interactive group problem solving. Prerequisite: PHYSICS 41 or equivalent. MATH 42 or MATH 51 or CME 100 or equivalent. Recommended corequisite: MATH 52 or CME 102.
What is electricity? What is magnetism? How are they related? How do these phenomena manifest themselves in the physical world? The theory of electricity and magnetism, as codified by Maxwell's equations, underlies much of the observable universe. Students develop both conceptual and quantitative knowledge of this theory. Topics include: electrostatics; magnetostatics; simple AC and DC circuits involving capacitors, inductors, and resistors; integral form of Maxwell's equations; electromagnetic waves. Principles illustrated in the context of modern technologies. Broader scientific questions addressed include: How do physical theories evolve? What is the interplay between basic physical theories and associated technologies? Discussions based on the language of mathematics, particularly differential and integral calculus, and vectors. Physical understanding fostered by peer interaction and demonstrations in lecture, and discussion sections based on interactive group problem solving. Prerequisite: PHYSICS 41 or equivalent. MATH 42 or MATH 51 or CME 100 or equivalent. Recommended corequisite: MATH 52 or CME 102.  Collection
 Stanford University Syllabi
Online 90. Studies of unconventional superconductivity [electronic resource] [2016]
 Cho, Weejee.
 2016.
 Description
 Book — 1 online resource.
 Summary

The physics of unconventional superconductors has been studied for decades but is still not well understood. The present thesis consists of two parts, each intended to shed light on some aspects of this longstanding problem. In the first part, I discuss, based on the Hubbard model in the weakcoupling limit, how the repulsion between electrons gives rise to Cooper pairing. I present simple rules that connect the features of the band structure to those of the gap function, as well as detailed numerical results for various model systems. In the second part, I focus on symmetry constraints on light reflection; a precise understanding of this issue is essential for identifying broken symmetries in various unconventional superconductors from polar Kerr effect measurements. Using a Green's function approach, I prove that the Onsager symmetry of the nonlocal electromagnetic response function implies the absence of the polar Kerr effect in backscattering.
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3781 2016 C  Inlibrary use 
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
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How are the motions of objects and the behavior of fluids and gases determined by the laws of physics? Students learn to describe the motion of objects (kinematics) and understand why objects move as they do (dynamics). Emphasis on how Newton's three laws of motion are applied to solids, liquids, and gases to describe phenomena as diverse as spinning gymnasts, blood flow, and sound waves. Understanding manyparticle systems requires connecting macroscopic properties (e.g., temperature and pressure) to microscopic dynamics (collisions of particles). Laws of thermodynamics provide understanding of realworld phenomena such as energy conversion and performance limits of heat engines. Everyday examples are analyzed using tools of algebra and trigonometry. Problemsolving skills are developed, including verifying that derived results satisfy criteria for correctness, such as dimensional consistency and expected behavior in limiting cases. Physical understanding fostered by peer interaction and demonstrations in lecture, and interactive group problem solving in discussion sections. Labs are an integrated part of the summer course. Prerequisite: high school algebra and trigonometry; calculus not required.
How are the motions of objects and the behavior of fluids and gases determined by the laws of physics? Students learn to describe the motion of objects (kinematics) and understand why objects move as they do (dynamics). Emphasis on how Newton's three laws of motion are applied to solids, liquids, and gases to describe phenomena as diverse as spinning gymnasts, blood flow, and sound waves. Understanding manyparticle systems requires connecting macroscopic properties (e.g., temperature and pressure) to microscopic dynamics (collisions of particles). Laws of thermodynamics provide understanding of realworld phenomena such as energy conversion and performance limits of heat engines. Everyday examples are analyzed using tools of algebra and trigonometry. Problemsolving skills are developed, including verifying that derived results satisfy criteria for correctness, such as dimensional consistency and expected behavior in limiting cases. Physical understanding fostered by peer interaction and demonstrations in lecture, and interactive group problem solving in discussion sections. Labs are an integrated part of the summer course. Prerequisite: high school algebra and trigonometry; calculus not required.  Collection
 Stanford University Syllabi
Online 92. Theory and measurements of emittance preservation in plasma wakefield acceleration [electronic resource] [2016]
 Frederico, Joel.
 2016.
 Description
 Book — 1 online resource.
 Summary

Plasma wakefield acceleration (PWFA) is a revolutionary approach to accelerating charged particles. In this dissertation, we present conditions for circular symmetry in the plasma wake. We present analysis of beam parameter and emittance matching, which predicts these values reach an equilibrium. We present and simulate a model for ion motion, and lay the foundation for simulations revealing emittance growth due to ion motion. By connecting a simple ion motion model and emittance theory, we calculate the emittance growth due to marginal ion motion to be minimal. We also present a proofofconcept of an emittance measurement of PWFA beams.
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Online 93. Topological phenomena in condensed matter physics [electronic resource] [2016]
 Jian, Chaoming.
 2016.
 Description
 Book — 1 online resource.
 Summary

In this thesis, we study the topological phenomena in 2+1 dimensional topologically ordered states with additional extrinsic structures. One type of extrinsic structures we will study in this thesis is extrinsic defect. We first introduce the conceptual scheme of extrinsic twist defects which are pointlike defects associated with symmetries of the 2+1 dimensional topological states. We explicitly study several classes of examples. In particular, we study several class the projective nonAbelian braiding statistics of the twist defects which are fundamentally different from the statistics of intrinsic excitations in topological systems. We also find an example where the projective nonAbelian statistics of twist defects can be exploited for universal topological quantum computation, while the host state itself is not suitable for this purpose. Apart from twist defects, extrinsic defects in 2+1 dimensional topological states can take various other forms including linelike defects and pointlike defects. For 2+1 dimensional Abelian topological states, we establish a general classification of all linelike and pointlike defects. We develop a general method to analyze the quantum dimensions of all the pointlike defects, a general understanding of their localized "parafermion" zero modes, and study the projective nonAbelian statistics of them. Another type of extrinsic structure this thesis focuses on is the layering structure of 2+1 dimensional topological states. We propose a general formalism for constructing a large class of 3+1 dimensional topological states by stacking layers of 2+1 dimensional topological states and introducing coupling between them. Using this construction, we can study interesting topological phenomena in 3+1 dimensions, including surface topological orders and 3+1 dimensional topological orders. As an interesting consequence of this construction, we obtain example systems with nontrivial braiding statistics between stringlike excitations. In addition to studying the stringstring braiding in the example system, we propose a generic topological field theory description which can capture both stringparticle and stringstring braiding statistics. Lastly, we provide a proof of a general identity for Abelian string statistics, and discuss an example system with nonAbelian strings.
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Online 94. Towards multiwavelength observations of relativistic jets from general relativistic magnetohydrodynamic simulations [electronic resource] [2016]
 Anantua, Richard Jude.
 2016.
 Description
 Book — 1 online resource.
 Summary

A methodology for reverse engineering current and anticipated observations of astrophysical relativistic jets using selfconsistent, general relativistic magnetohydrodynamic (GRMHD) simulations is detailed from datahosting and manipulation to mimicking instrumentspecific properties such as point spread function convolution. This pipeline handles particle acceleration prescriptions, synchrotron and inverse Compton emission and absorption, Doppler boosting, timedependent transfer of polarized radiation and lighttravel time effects. Application of this pipeline to lowfrequency radio observations is exemplified using the famous jet in the giant elliptical galaxy M87. Highfrequency gammaray observations are represented by the powerful quasar 3C 279. Though the work presented here focuses on a single simulation of a magnetically arrested disk and a windcollimated, approximately forcefree jet, it can readily be adapted to simulations with different spatiotemporal resolutions and/or plasma initial conditions. Stationary, axisymmetric semianalytic models are also developed, providing a quantitative understanding of the simulated jet flow and its electromagnetic properties. Using the 3D timedependent \say{observing} routines for synchrotron models, predictions such as bilateral asymmetry of intensity maps and enhanced limb brightening for models with high velocity shear are advanced. Using gamma ray prescriptions in the routines resulted in rapid variability. Userfriendly Python and UNIX guides are included for didactic purposes. With the advent of the stateoftheart gamma ray Cerenkov Telescope Array, the Event Horizon Telescope which promises to resolve Schwarzshild radius ($r_S$) scale features at the Galactic Center and M87 and more sophisticated GRMHD simulations with similar resolution coupled with dynamical range $10^0r_S$$10^5r_S$, direct comparison of simulation and observation in this work may facilitate the understanding and prediction of the physical nature of relativistic jets in the near future.
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Online 95. Twodimensional spatial imaging of charge transport in germanium crystals at cryogenic temperatures [electronic resource] [2016]
 Moffatt, Robert A.
 2016.
 Description
 Book — 1 online resource.
 Summary

In this dissertation, I describe a novel apparatus for studying the transport of charge in semiconductors at cryogenic temperatures. The motivation to conduct this experiment originated from an asymmetry observed between the behavior of electrons and holes in the germanium detector crystals used by the Cryogenic Dark Matter Search (CDMS). This asymmetry is a consequence of the anisotropic propagation of electrons in germanium at cryogenic temperatures. To better model our detectors, we incorporated this effect into our Monte Carlo simulations of charge transport. The purpose of the experiment described in this dissertation is to test those models in detail. Our measurements have allowed us to discover a shortcoming in our most recent Monte Carlo simulations of electrons in germanium. This discovery would not have been possible without the measurement of the full, twodimensional charge distribution, which our experimental apparatus has allowed for the first time at cryogenic temperatures.
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Online 96. Ultrafast studies of nonequilibrium electronphonon and phononphonon interactions in photoexcited lead telluride [electronic resource] [2016]
 Jiang, Mason Patrick.
 2016.
 Description
 Book — 1 online resource.
 Summary

PbTe is a member of the group IVVI semiconducting compounds that distinctly crystallize in three closely related structures (cubic, rhombohedral, orthorhombic). The determination of the structure depends on a delicate balance between levels of ionicity and covalency. Classified as an incipient ferroelectric, PbTe lies very close to the cubic/rhombohedral phase boundary, crystallizing in a paraelectric rocksalt cubic configuration, but with a proclivity to distort into a ferroelectric state, although never doing so. This instability leads to anomalous characteristics in the lattice dynamics of PbTe and is thought to contribute to its naturally low thermal conductivity, which makes it so effective as a thermoelectric compound. Specifically, recent inelastic neutron scattering (INS) measurements reveal that the soft transverse optical (TO) mode of the material is far more dispersive than expected (less dispersive trajectory measured in past INS studies) and features a splitpeak lineshape at zone center, both indicative of a "giant" anharmonicity. The zone center frequency of this mode is the typical indicator of the nearness to a ferroelectric transition. To more deeply understand the microscopic mechanisms that link the structural instability of PbTe with its unusual phonon behavior, an ultrafast experimental approach is utilized in this thesis to characterize the material. In this tactic, the compound is impulsively photoexcited away from its ground state and a unique perspective is offered on the interactions that govern its relaxation back to equilibrium. Several variations of timeresolved pumpprobe methods are employed. One highlighted result proceeds from a series of fluence, temperature, and pressure dependent IR pumpIR probe measurements on PbTe, which show previously unreported, prominent reflectivity oscillations from the rocksaltstructured material. The oscillations increase in amplitude with higher fluence and temperature while blueshifting in frequency with higher pressure. It is determined that these oscillations originate from the photoexcitation of a TOTA (transverse acoustic) combination via the secondorder Raman mechanism. Another result stems from time and momentum resolved xray measurements on PbTe, which show evidence that electronphonon interactions play a significant role in the material's equilibrium ferroelectric instability. Here, we characterize the dispersion of correlated pairs of phonons with equal and opposite momenta produced by the absorption of pump pulses near the energy of the direct band gap. From the dispersion data away from zone center coupled with constrained density functional theory (CDFT) calculations, we find that photoexcitation leads to the TO branch hardening near zone center and softening near zone edge (X point). This is further tied to the weakening of longrange forces along the cubic direction and in the band picture, a reduction of the Peierlslike electronic instability. All of this reinforces the paraelectric state. It is thus determined that electronphonon coupling drives ferroelectric instability in PbTe. Furthermore, from the dispersion data very near zone center, we find a highly dispersive feature that is identified as a heavily screened longitudinal optical (LO) phonon mode. This feature is attributed to the high photoexcitation density in the measurements and is reminiscent of LO mode softening seen in past INS studies of PbTe. It is concluded that this similarity is due to the effective equivalence between photoexcitation in our measurements and relatively high carrier doping in the samples of the past studies. This is significant since it reconciles the inconsistency between the dispersion results of the aforementioned recent INS measurements (measured on less doped samples) with those seen in the older studies.
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Online 97. W16PHYSICS10701 : Intermediate Physics Laboratory II: Experimental Techniques and Data Analysis. 2016 Winter [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

Experiments on lasers, Gaussian optics, and atomlight interaction, with emphasis on data and error analysis techniques. Students describe a subset of experiments in scientific paper format. Prerequisites: completion of PHYSICS 40 or PHYSICS 60 series, and PHYSICS 70 and PHYSICS 105. Recommended pre or corequisites: PHYSICS 120 and 130. WIM
Experiments on lasers, Gaussian optics, and atomlight interaction, with emphasis on data and error analysis techniques. Students describe a subset of experiments in scientific paper format. Prerequisites: completion of PHYSICS 40 or PHYSICS 60 series, and PHYSICS 70 and PHYSICS 105. Recommended pre or corequisites: PHYSICS 120 and 130. WIM  Collection
 Stanford University Syllabi
Online 98. W16PHYSICS13001 : Quantum Mechanics I. 2016 Winter [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

The origins of quantum mechanics and wave mechanics. Schrodinger equation and solutions for onedimensional systems. Commutation relations. Generalized uncertainty principle. Timeenergy uncertainty principle. Separation of variables and solutions for threedimensional systems; application to hydrogen atom. Spherically symmetric potentials and angular momentum eigenstates. Spin angular momentum. Addition of angular momentum. Prerequisites: PHYSICS 65 or PHYSICS 70 and MATH 131P or MATH 173. MATH 173 can be taken concurrently. Pre or corequisites: PHYSICS 120.
The origins of quantum mechanics and wave mechanics. Schrodinger equation and solutions for onedimensional systems. Commutation relations. Generalized uncertainty principle. Timeenergy uncertainty principle. Separation of variables and solutions for threedimensional systems; application to hydrogen atom. Spherically symmetric potentials and angular momentum eigenstates. Spin angular momentum. Addition of angular momentum. Prerequisites: PHYSICS 65 or PHYSICS 70 and MATH 131P or MATH 173. MATH 173 can be taken concurrently. Pre or corequisites: PHYSICS 120.  Collection
 Stanford University Syllabi
Online 99. W16PHYSICS16001 : Introduction to Stellar and Galactic Astrophysics. 2016 Winter [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

Observed characteristics of stars and the Milky Way galaxy. Physical processes in stars and matter under extreme conditions. Structure and evolution of stars from birth to death. White dwarfs, planetary nebulae, supernovae, neutron stars, pulsars, binary stars, xray stars, and black holes. Galactic structure, interstellar medium, molecular clouds, HI and HII regions, star formation, and element abundances. Undergraduates register for PHYSICS 160. Graduate students register for PHYSICS 260. (Graduate students will be required to complete additional assignments in a format determined by the instructor.) Prerequisite: PHYSICS 121.
Observed characteristics of stars and the Milky Way galaxy. Physical processes in stars and matter under extreme conditions. Structure and evolution of stars from birth to death. White dwarfs, planetary nebulae, supernovae, neutron stars, pulsars, binary stars, xray stars, and black holes. Galactic structure, interstellar medium, molecular clouds, HI and HII regions, star formation, and element abundances. Undergraduates register for PHYSICS 160. Graduate students register for PHYSICS 260. (Graduate students will be required to complete additional assignments in a format determined by the instructor.) Prerequisite: PHYSICS 121.  Collection
 Stanford University Syllabi
Online 100. W16PHYSICS17101 : Thermodynamics, Kinetic Theory, and Statistical Mechanics II. 2016 Winter [2016]
 Stanford University. Department of Physics (Sponsor)
 Stanford (Calif.), 2016
 Description
 Book — 1 text file
 Summary

Meanfield theory of phase transitions; critical exponents. Ferromagnetism, the Ising model. The renormalization group. Dynamics near equilibrium: Brownian motion, diffusion, Boltzmann equations. Other topics at discretion of instructor. Prerequisite: PHYSICS 170. Recommended pre or corequisite: PHYSICS 130.
Meanfield theory of phase transitions; critical exponents. Ferromagnetism, the Ising model. The renormalization group. Dynamics near equilibrium: Brownian motion, diffusion, Boltzmann equations. Other topics at discretion of instructor. Prerequisite: PHYSICS 170. Recommended pre or corequisite: PHYSICS 130.  Collection
 Stanford University Syllabi