Alumni

Degree Date: December, 2013
Kinga Partyka's picture
Kinga Partyka
Bonnie Fleming


Exclusive Muon-Neutrino Charged Current mu+Np topologies in ArgoNeuT
Neutrinos remain among the least understood fundamental particles even after decades of study. As we enter the precision era of neutrino measurements bigger and more sophisticated detectors have emerged. The leading candidate among them is a Liquid Argon Time Projection Chamber (LArTPC) detector technology due to its bubble-like chamber imaging, superb background rejection and scalability. It is a perfect candidate that will aim to answer the remaining questions of the nature of neutrino and... more
William Pontius's picture
William Pontius
Thierry Emonet


The Molecular Origins and Functional Role of Noise in a Simple Sensory Network
Biological pathways perform calculations with often-small numbers of constituent molecules, leading to potentially significant variability in their output. In this thesis, I use the chemotaxis pathway of the bacterium Escherichia coli as a model to investigate the molecular origins of large temporal fluctuations and their consequences for cellular behavior. The bacterial chemotaxis pathway is a simple sensory network that performs temporal comparisons of external chemical stimuli, enabling the... more
Matthew Reed's picture
Matthew Reed
Robert Schoelkopf
Research Staff Physicist

HRL Laboratories


Entanglement and Quantum Error Correction with Superconducting Qubits
A quantum computer will use the properties of quantum physics to solve certain computational problems much faster than otherwise possible. One promising potential implementation is to use superconducting quantum bits in the circuit quantum electrodynamics (cQED) architecture. There, the low energy states of a nonlinear electronic oscillator are isolated and addressed as a qubit. These qubits are capacitively coupled to the modes of a microwave-frequency transmission line resonator which serves... more
Charles Riley's picture
Charles Riley
Jack Sandweiss
Manager, Finance & Strategy

ConnectGen LLC


Searching for Local Parity Violation in Heavy Ion Collisions
Parity violation of the strong interaction is prohibited globally, however, it may be possible for parity to be violated locally in hot, dense, and deconfined QCD matter created in heavy ion collisions. Microscopic parity-odd domains in QCD are the consequence of topologically non-trivial configurations of gauge fields, and may be observable in heavy ion collisions due to the so called Chiral Magnetic Effect (CME). The CME predicts that provided a strong magnetic field (produced in a non-... more
Flavius Schackert's picture
Flavius Schackert
Michel Devoret
Software Engineer, Machine Learning


A Practical Quantum-Limited Parametric Amplifier Based on the Josephson Ring Modulator
This dissertation has addressed the problem of developing the Josephson Parametric Converter (JPC) as a practical phase-preserving microwave parametric amplifier operating at the quantum limit of added noise. The device consists of two superconducting resonators coupled through the Josephson Ring Modulator (JRM), which in essence consists of a loop of four identical Josephson tunnel junctions, threaded by an applied magnetic flux. The nonlinearity of the JRM is of the tri-linear form XYZ... more
Adam Sears's picture
Adam Sears
Robert Schoelkopf


Extending Coherence of Superconducting Qubits: from microseconds to milliseconds
Circuit quantum electrodynamics (Circuit QED) is the extremely successful framework for studying quantum devices developed along with the transmon, a superconducting charge qubit with an insensitivity to several types of dephasing. It involves the description of superconducting qubits and harmonic oscillators as quantized circuits. This thesis describes the implementation of two experiments that reduce circuit QED to its simplest components. Both experiments utilize elements that are known to... more
Degree Date: May, 2013
Sourpouhi Bedikian's picture
Sourpouhi Bedikian
Sarah Demers


A Search for the Charged Higgs: Using Tau Polarimetry with Proton-Proton Collisions at the ATLAS Detector
A search for a 130 GeV charged Higgs boson in ttbar events containing a tau lepton is presented. Tau polarimetry is used in order to distinguish the signal, t → H±b → τνb, from the dominant Standard Model background, t → W±b → τνb. The signal extraction is performed by a log-likelihood template fit. The dataset corresponds to an integrated luminosity of 4.6 fb^−1 of sqrt(s)=7 TeV proton-proton collisions collected with the ATLAS detector in... more
Christopher Gilbreth's picture
Christopher Gilbreth
Yoram Alhassid
Postdoc Assoc Physics

FASPHY Physics Nuclear - Theoretical


Ultracold Fermi Gases: Effective Interactions and Superfluidity
Cold atomic Fermi gases are clean, highly experimentally tunable systems with connections to many different fields of physics. However, in the strongly-interacting regime they are nonperturbative and difficult to study theoretically. One challenge is to calculate the energy spectra of few-body cold atom systems along the crossover from a gas described by a Bose-Einstein condensate (BEC) to a gas described by Bardeen-Cooper-Schrieffer (BCS) theory. The configuration-interaction (CI) method is... more
Archana Kamal's picture
Archana Kamal
Michel Devoret
Assistant Professor

Universty of Massachusetts Lowell


Nonreciprocity in active Josephson junction circuits
I will present different flavors of nonreciprocal photon dynamics realized using active parametric circuits based on Josephson junctions. The motivation stems from developing non-magnetic alternatives to existing nonreciprocal devices, invariably employing magnetic materials and fields and hence limited in their application potential for use with on-chip microwave superconducting circuits. The main idea rests on the fact the “pump” wave (or the carrier) in an active nonlinear system... more
Zuhair Khandker's picture
Zuhair Khandker
Walter Goldberger
Postdoctoral Researcher

University of Illinois at Urbana-Champaign


Embedding Methods for Conformal Field Theor
Conformal field theories (CFTs) are highly constrained by symmetry. For instance, based on symmetry considerations alone one can derive constraints on the form of correlators and on the scaling dimensions of certain operators. However, the full implications of symmetry are still far from understood, i.e. we still do not know the extent to which conformal symmetry constrains the space of all possible CFTs. In the non-supersymmetric setting, the embedding-space formalism for CFTs has proven to be... more
Nicholas Masluk's picture
Nicholas Masluk
Michel Devoret
Research Staff Member / Manager

IBM


Purifying the environment of the fluxonium artificial atom
Fluxonium is a highly anharmonic artificial atom, which makes use of an array of large Josephson junctions to shunt the junction of a Cooper-pair box for protection from charge noise. At microwave frequencies the array forms a "superinductance", a superconducting inductance whose impedance exceeds the resistance quantum h/(2e)^2 = 6.5 kOhm. The first excited state transition frequency is widely tunable with flux, covering more than five octaves, yet the second excited state remains... more
John Murray's picture
John Murray
Xiao-Jing Wang
Assistant Professor of Psychiatry and Neuroscience

Yale University


Website
Specialization of neural circuits for cognition: linking structure to function through dynamics
The brain achieves flexible cognition through specialization of cortical areas for different functions. To subserve working memory, prefrontal cortex can maintain a persistent pattern of activity in the absence of a stimulus, whereas sensory areas do not. What is the neural circuit basis of specialized function? Strong recurrent structure in synaptic connections endows a circuit with attractor dynamics that can subserve cognitive function. This suggests that areas achieve specialization in part... more
Richard Wall's picture
Richard Wall
Paul Tipton


A study of heavy flavor quarks produced in association with top quark pair events at sqrt(s) = 7 TeV using the ATLAS detector
In this thesis, we show evidence for the production of ttbar + b + X and ttbar + c + X, together refered to as ttbar + HF, at the Large Hadron Collider. A sample of dilepton ttbar candidate events with three or more b-tagged jets is used to isolate a $\ttbar$ sample rich in extra heavy flavor jets. A fit to the vertex mass distribution for the b-tagged jets in this region is performed to extract the flavor composition of the additional b-tags. This measurement is converted to a cross-section... more
Brian Walsh's picture
Brian Walsh
Tobias Golling
Economist

World Bank


Website
SEARCH FOR STOP SQUARK PAIR PRODUCTION IN FINAL STATES WITH ONE ISOLATED LEPTON, JETS, AND MISSING TRANSVERSE MOMENTUM IN SQRT(S) = 7 TeV COLLISIONS USING 4.7 fb^(-1) OF ATLAS DATA
A cut-and-count search for stop squark pair production in pp collisions at √s = 7 TeVwith 4.71 fb−1 of 2011 ATLAS data is presented. Events with one isolated lepton, four or more jets, and missing transverse energy are selected to study a simplified model of stop squark decay to one top quark and one neutralino χ ̃01. Data is seen to be compatible with Standard Model-only hypothesis, and model-dependent as well as model-independent exclusion limits are set.
Degree Date: December, 2012
Steven Eckel's picture
Steven Eckel
Steve Lamoreaux
Research Scientist

National Institute of Standards and Technology


A Search for the Electron EDM using Europium-Barium Titanates
The discovery of a permanent electric dipole moment (EDM) of a fundamental particle would prove a great discovery in modern physics, as such an EDM would violate some of the core symmetries of the fundamental forces of nature. Many models that go beyond the standard model of particle physics produce EDMs with magnitudes approaching the level detectable by the next generation of experiments. One possibility for such an experiment involves the use of a solid sample at low temperatures. In a... more