# Alumni

 Kyle VanderWerfCorey O'Hern Geometry and Contact Mechanics of Athermal Jammed Packings of Frictionless Spherical and Nonspherical ParticlesI perform computational studies of quasistatically jammed packings of frictionless particles of a variety of shapes. Each of the four studies presented in this dissertation focuses primarily on the connection between the mechanical and geometric properties of these packings – specifically, how physical aspects such as force and torque balance, pressure, and shear and bulk moduli correlate with (a) constituent particle shape, (b) the degree of particle ordering in packings, and (c) the... more Christian WeberKeith Baker Research Associate PhysicsBrookhaven National LabNew Search for H→ZZ_d→4l using pp collision data at √s=13 TeV with the ATLAS detectorIn 2012 the ATLAS and CMS experiments both reported the discovery of a new particle in the remnants of high-energy proton-proton collisions. The particles properties were consistent with the ones of the Standard Model Higgs boson. Its discovery, 58 years after its postulation, marked the completion of the Standard Model of Particle Physics.   Subsequent data taking at both experiments continued to record Higgs boson decays. With this increased dataset, we are now... more Hao YanSimon Mochrie Positional Fluctuations in Synthetic and Living Polymer SystemsChromatin organization is inextricably linked to its dynamics. The loop extrusion factor (LEF) model provides a framework for how topologically associating domains (TADs) arise: cohesin or condensin extrude DNA loops, until they encounter boundary elements, namely CTCF. However, a characteristic subdiffusive behavior of MSD is observed in fission yeast on the seconds timescale and experiments show that cohesin or condensin largely constrains chromatin mobility. Such finding is inconsistent with... more
 Robert BlumSean Barrett Postgraduate Associate (Barrett)Yale UniversityApplying novel NMR techniques to many-body spin systems, and novel reconstruction techniques to NMR dataThis experimental thesis focuses on two distinct themes: developing NMR techniques to probe many-body spin systems, and extracting the maximum amount of information from the minimum amount of data. For the first theme, I describe the first NMR observations of discrete time crystal signatures. A discrete time crystal (DTC) is a many-body quantum state where a driven system exhibits discrete time translational symmetry breaking. A surprising aspect of our DTC signatures is that they were detected... more Luke BurkhartRob Schoelkopf Postgraduate AssociateYale University, Applied PhysicsError-Detected Networking for 3D Circuit Quantum ElectrodynamicsQuantum machines have the potential to serve as groundbreaking tools for scientific discovery in the coming decades. As the complexity of these devices increases, it may be necessary to borrow ideas from complex classical systems, and build them in a modular fashion, with independently designed, optimized, and tested components, networked together into a functioning whole. To build a modular machine from superconducting circuits requires the ability to perform operations between quantum bits... more Arpit DuaMeng Cheng & Liang Jiang UQM-IQIM Postdoctoral scholarCaltechStructure of fracton stabilizer models In recent years the study of topological phases of matter has moved to the forefront of theoretical condensed matter physics. This has been fueled in part by the theorized existence of exotic phases of matter that can serve as topological quantum memories and computers. The classification of topological phases of matter in two spatial dimensions in terms of anyon theories, or modular tensor categories, and chiral central charges forms the cornerstone of the subject. For the special case of 2D... more Raymond EhlersHelen Caines Postdoctoral AssociateOak Ridge National Lab Jet-Hadron Correlations Measured in Pb--Pb Collisions at $\sqrt{s_{\text{NN}}} = 5.02$ TeV with ALICEQuantum Chromodrynamics (QCD) describes the interactions of quarks and gluons. Due to asymptotic freedom, sufficiently high energy density can cause matter to transition to a deconfined state of matter known as the Quark-Gluon Plasma. As partons propagate through this QCD medium, which can be formed in ultra-relativistic heavy-ion collisions, they lose energy and the resulting jets are known to be modified in a phenomena known as jet quenching. This thesis investigates potential path length... more Judith HoellerNicholas Read Postdoctoral AssociateTBDTopological quantization of Berry phases in quantum and classical systemsBerry phases are known to occur for a spin 1/2 in a slowly varying magnetic field in quantum mechanics, and for the polarization of light in a gently twisted optical fiber in classical optics. Such Berry phases take on continuous values. I describe two systems in which Berry phases are topologically quantized to discrete values: (1) cold atoms in accelerated optical lattices, and (2) dissipative two level systems coupled to radiation with a slowly varying phase offset. (1) Cold atoms in... more Luyao JiangJack Harris Wells FargoNonreciprocal dynamics in a cryogenic optomechanical systemNonreciprocity in various branches of physics has been studied for more than a century, e.g., from classical to quantum mechanics, and from particle to condensed matter. It is particularly interesting to consider nonreciprocal phenomenon in open (non-hermitian) systems. In this dissertation, I use a cryogenic cavity optomechanical system to demonstrate robust nonreciprocal interactions between two phononic resonators. The nonreciprocity, either transient or static, is realized via the cavity... more Norman LamJohn Murray Postdoctoral AssociateMITInhibitory Regulation of Cognitive Functions in Cortical and Thalamic Circuits: Computational Mechanisms and Experimental PredictionsCognitive behaviors fundamentally arise from the interactions of numerous neurons in the brain. However, while neuronal properties are well-characterized, how an ensemble of interconnected neurons acts is generally not apparent from the single-neuron dynamics. Computation in specific circuits of neuronal populations is known to reflect key variables in core cognitive functions, such as decision making, although the underlying mechanisms are not fully understood. There thus are explanatory gaps... more Claudia LauCharles Ahn Structural characterization of epitaxial oxide heterostructures via X-ray scatteringThe impact of atomic-scale structural distortions on the transport properties of epitaxial thin film oxides and their interfaces is investigated through high resolution surface x-ray diffraction. The crystalline thin films studied are the metallic oxides (La,Sr)TiO3 and LaNiO3, the high mobility oxide BaSnO3, the high dielectric oxide LaInO3, and the ferroelectric oxide Pb(Zr,Ti)O3. Films were grown on SrTiO3 and DyScO3 commercial substrates by the physical vapor deposition techniques off-axis... more Catherine MatulisDamon Clark EngineerMathWorksContrast adaptation in Drosophila direction-selective circuitsIn visual systems, neurons adapt both to the mean light level and to the range of light levels, or the contrast. Contrast adaptation has been studied extensively, but it remains unclear how it is distributed among neurons in connected circuits, and how early adaptation affects subsequent computations. In this study, we investigated temporal contrast adaptation in neurons across Drosophila's visual motion circuitry. Several ON-pathway neurons showed strong adaptation to changes in contrast... more Shantanu MundhadaMichel Devoret Quantum EngineerQuantum Circuit, Inc.Hardware-efficient autonomous quantum error correctionThe promise of quantum speedup in information processing is not yet fulfilled in a useful quantum algorithm due to the susceptibility of quantum information to decoherence. This makes quantum error correction (QEC) a vital area of research. The vast majority of QEC protocols, however, come with an overwhelming hardware and software overhead. For superconducting quantum circuits, it is possible to minimize this overhead by hardware-efficient encoding in infinite dimensional Hilbert spaces of... more Kyungjoo NohLiang Jiang Quantum Research ScientistAmazon Web ServicesWebsiteQuantum computation and communication in bosonic systemsQuantum computation and communication are important branches of quantum information science. However, noise in realistic quantum devices fundamentally limits the utility of these quantum technologies. A conventional approach towards large-scale and fault-tolerant quantum information processing is to use multi-qubit quantum error correction (QEC), that is, to encode a logical quantum bit (or a logical qubit) redundantly over many physical qubits such that the redundancy can be used to detect... more Brooke RussellBonnie Fleming Owen Chamberlain Postdoctoral FellowLawrence Berkeley National Laboratory An Electron Neutrino Appearance Search in MicroBooNE with 5$\times$10$^{19}$ POTMicroBooNE is a single-phase liquid argon time projection chamber (LArTPC) short-baseline accelerator neutrino experiment located at Fermi National Accelerator Laboratory in the Booster Neutrino Beam. MicroBooNE's foremost scientific objective is to definitively resolve the low-energy excess of single shower electromagnetic events seen by the precursor MiniBooNE experiment. This thesis examines a small fraction of early MicroBooNE data. By leveraging fine-grained drifted ionization... more