Alumni

Degree Date: May, 2017

Corey Adams
Bonnie Fleming

First Detection of Low Energy Electron Neutrinos in Liquid Argon Time Projection Chambers


Electron neutrino appearance is the signature channel to address the most pressing questions in neutrino oscillations physics, at both long and short baselines. This includes the search for CP violation in the neutrino sector, which the U.S. flagship neutrino experiment DUNE will address. In addition, the Short Baseline Neutrino Program at Fermilab (MicroBooNE, SBND, ICARUS-T600) searches for new physics, such as sterile neutrinos, through electron neutrino appearance. Liquid argon time... more

Victor Albert
Liang Jiang

Lindbladians with multiple steady states: theory and applications


Lindbladians, one of the simplest extensions of Hamiltonian-based quantum mechanics, are used to describe decay and decoherence of a quantum system induced by that system's environment. Traditionally, an environment is viewed as detrimental to fragile quantum properties. Nevertheless, it offers the ability to drive the system toward exotic phases of matter, which may be difficult to stabilize in nature, or toward protected subspaces, which can be used to store and process quantum... more

Marco Bonett-Matiz
Yoram Alhassid

Statistical and Spectroscopic Properties of Nuclei in the Shell Model Monte Carlo Method


The predictive power of the interacting shell model in describing properties of nuclei is restricted by the limitations of conventional diagonalization techniques. The shell model Monte Carlo (SMMC) method allows the calculation of thermal properties in very large model spaces, much beyond what is possible with exact diagonalization. In particular, the SMMC has become the state-of-the-art method for the calculation of statistical properties of nuclei. The total state density that is... more

Mehmet Dogan
Sohrab Ismail-Beigi

Ab initio studies of ferroelectric thin films


Epitaxial interfaces between metal oxides and semiconductors have been of significant research interest due to their potential use in electronic device applications. Thin films of metal oxides can display many functional physical properties, an important example of which is ferroelectricity. Ferroelectric thin metal oxide films grown on semiconductors can enable non-volatile transistors, where the state of the device is encoded in the polarization state of the oxide which determines the... more

Alexandru Bogdan Georgescu
Sohrab Ismail-Beigi

New Methods and Phenomena in The Study of Correlated Complex Oxides


Transition metal oxides have long been an important subject of study, both theoretically and experimentally. The wide array of phases possible in their bulk forms (high T$_c$ superconductivity, colossal magnetoresistance, ferroelectricity, etc.) makes them of scientific and technological significance, while relatively recent materials deposition techniques have allowed researchers to grow new, 'artificial' materials in the form of heterostructures and thin films. These structures offer... more

Peiyuan Mao
Meg Urry

Blazar Demographics: Intrinsic Properties of Jet-Dominated Active Galactic Nuclei


Blazars with their Doppler-boosted relativistic jets are perfect laboratories to study jet physics and provide crucial insights into jet mechanism, black hole spin, and growth history of the host galaxy. However, the blazar samples we observe are highly biased subsets of the true population because of the complicated shape of their spectral energy distributions. Thus to infer the intrinsic properties of blazars we have to extrapolate from the biased samples — and there are two opposing... more

Brendon O'Leary
David DeMille

In search of the electron's electric dipole moment in thorium monoxide: an improved upper limit, systematic error models, and apparatus upgrades


Searches for violations of discrete symmetries can be sensitive probes of physics beyond the Standard Model. Many models, such as supersymmetric theories, introduce new particles at higher masses that include new CP-violating phases which are thought to be of order unity. Such phases could generate measurable permanant electric dipole moments (EDMs) of particles. The ACME collaboration has measured the electron’s EDM to be consistent with zero with an order of magnitude improvement in... more

Saehanseul Oh
John Harris

Correlations in particle production in proton-lead and lead-lead collisions at the LHC


In high-energy heavy-ion collisions at the Large Hadron Collider (LHC), a hot and dense state of matter called the Quark-Gluon Plasma (QGP) is formed. The initial collision geometry and the subsequent expansion during the QGP stage result in the correlations of produced particles, through which the properties of the QGP can be investigated. Two analyses based on the geometrical correlations of produced particles, one in proton-lead (p–Pb) collisions and the other in lead-lead (Pb–Pb... more

Andrei Petrenko
Robert Schoelkopf

Enhancing the Lifetime of Quantum Information with Cat States in Superconducting Cavities


The field of quantum computation faces a central challenge that has thus far impeded the full-scale realization of quantum computing machines: decoherence.  Remarkably, however, protocols in Quantum Error Correction (QEC) exist to correct qubit errors and thus extend the lifetime of quantum information.  Reaching the "break-even" point of QEC, at which a qubit's lifetime exceeds the lifetime of the system's constituents, has thus far remained an outstanding goal.... more

Toshihiko Shimasaki
David DeMille

Continuous Production of 85Rb133Cs Molecules in the Rovibronic Ground State via Short-Range Photoassociation


We present our results on continuous production of ultracold ^{85}Rb^{133}Cs molecules in the rovibronic ground state via short-range photoassociation (PA). Starting with ultracold Rb and Cs atoms trapped in dual-species dark-SPOT MOT, we photoassociate a pair of Rb and Cs atoms into an excited molecular state, which decays into the electronic ground state by spontaneous emission. We apply depletion spectroscopy to the RbCs system and establish a rotationally-resolved, state-selective detection... more

Jukka Vayrynen
Leonid Glazman

Electron transport along the edge of a topological insulator


A two-dimensional topological insulator has a gap for bulk excitations, but conducts on its boundaries via gapless edge modes. Time-reversal symmetry prohibits elastic backscattering of electrons propagating within the edge, leading to quantized conductance at zero temperature. Inelastic backscattering, present at finite temperature, breaks the quantization and  increases the edge resistance; the resistance of a long edge acquires a linear dependence on its length. A phenomenological... more
Degree Date: December, 2016

Filip Kos
David Poland

Bootstrapping 3D CFTs


We use the method of conformal bootstrap to systematically study the space of allowed conformal field theories (CFT) in three spacetime dimensions. We consider the crossing symmetry equations coming from the correlators of several lowest dimension operators in a given CFT and show how to setup the semidefinite program to explore the constraints implied by the equations. Constraints lead to general bounds on dimensions and 3-point functions of the operators in CFT. Three classes of CFTs... more

Tomomi Sunayama
Nikhil Padamanabhan

Using galaxy surveys as a precision tool to measure dark energy


Future surveys will provide a deeper understanding of dark energy, dark matter, and early universe physics through the measurements of large scale structure. In particular, the baryon acoustic oscillation (BAO) method and the redshift-space distortion (RSD) method aim to achieve sub-percent precision on cosmological parameters. Understanding and reducing the systematics caused by the non-linear evolution of gravitational structures and galaxy formation and evolution is crucial for future galaxy... more

Mitchell Underwood
Jack Harris

Cryogenic Optomechanics with a Silicon Nitride Membrane


The field of optomechanics involves the study of the interaction between light and matter via the radiation pressure force. Though the radiation pressure force is quite weak compared with forces we normally experience in the macroscopic world, modern optical and microwave resonators are able to enhance the radiation pressure force so that it can be used to both measure and control the motion of macroscopic mechanical oscillators. Recently, optomechanical systems have reached a regime where the... more
Degree Date: May, 2016

Rostislav Boltyanskiy
Eric Dufresne

Mechanical Response of Single Cells to Stretch


A living cell is a complex soft matter system far from equilibrium. While it consists of components with definite mechanical properties such as stiffness, viscosity, and surface tension, the mechanics of a cell as a whole are more elusive. We explore cell mechanics by stretching single fibroblast cells and simultaneously measuring their traction stresses. Upon stretch there is a sudden, drastic increase in traction stresses, often followed by a relaxation over a time scale of ~1min. Upon... more

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