# Alumni

 Nicholas MaslukMichel Devoret Research Staff Member / ManagerIBMPurifying the environment of the fluxonium artificial atomFluxonium 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 MurrayXiao-Jing Wang Assistant Professor of Psychiatry and NeuroscienceYale UniversityWebsiteSpecialization of neural circuits for cognition: linking structure to function through dynamicsThe 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 WallPaul Tipton A study of heavy flavor quarks produced in association with top quark pair events at sqrt(s) = 7 TeV using the ATLAS detectorIn 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 WalshTobias Golling EconomistWorld BankWebsiteSEARCH 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 DATAA 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.
 Steven EckelSteve Lamoreaux Research ScientistNational Institute of Standards and TechnologyA Search for the Electron EDM using Europium-Barium TitanatesThe 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 Matthew PhillipsGordon M. Shepherd HRL LaboratoriesSensory Processing in the Olfactory Bulb: From Lateral Inhibition to BehaviorSensory perception is the fundamental process by which all organisms gain knowledge of their world. Perceptions arise from stimulations of sensory receptors that are translated into neuronal signals. These signals become processed and refined greatly before reaching conscious awareness in higher brain areas. Understanding the mechanisms and functions of this processing is a significant and major challenge for science. The use of model systems, such as the mammalian olfactory system, is helpful... more Hasuk Francis SongKaryn Le Hur Research ScientistDeepMindEntanglement in Quantum Many-Body SystemsThe scaling of entanglement entropy and, more recently, the full entanglement spectrum have become useful tools for characterizing certain universal features of quantum many-body systems. We motivate the importance of entanglement in the study of many-body systems by considering the “gratuitously big” size of Hilbert space and the need for generic ansatzes that efficiently represent useful wave functions. In addition, we study the scaling of the entanglement entropy in the two-... more
 Hanghui ChenSohrab Ismail-Beigi Postdoctoral AssociateColumbia UniversityA first principles study of oxide interfacesBoth theoretically and experimentally, enormous progress has been made toward understanding and controlling materials at the atomic scales. The advances in thin film deposition techniques make it possible to grow artificially designed heterostructures that do not exist in nature. The theoretical developments of ab initio calculations combined with the rapid increase of computational capability enable scientists to analyse data, make predictions and even design experiments from numerical... more Andrew JayichJack Harris Postdoctoral AssociateCaltechLaser cooling a 261 kHz harmonic oscillatorOptomechanics is a diverse field where mechanical harmonic oscillators are coupled to an optical field via radiation pressure. The mechanical devices range from atom clouds and nanotubes up to the kilogram scale mirrors used in the LIGO observatories. The starting point for many interesting measurements begins with the mechanical device in its ground state, where it has less than a phonon worth of energy. In Jack Harris's lab we are working to cool a mechanical membrane to its ground state... more Benjamin KaplanPaul L. Tipton Postdoctoral AssociateNYUTesting the Standard Model of Particle Physics: A Search for New Phenomena in Multilepton Events with the ATLAS detector at the LHCAn excess of events over the Standard Model predictions in final states with three or more high momentum charged leptons would constitute evidence of new physical processes. Presented is a generic search for new phenomena in such events. To reduce the largest Standard Model backgrounds, events consistent with the production of a Z boson are rejected. Events are selected from 1.02 fb$^{-1}$ of proton-proton collision data recorded by the ATLAS detector at $\sqrt{s}$ = 7 TeV. There is no... more Sarah LockwitzPaul Tipton Postdoctoral AssociateFermi LabA Search for the Standard Model Higgs Boson in CDF II DataThis dissertation presents a search for the standard model Higgs boson in the associated production process proton anti-proton to ZH to electron positron b quark anti-b quark. Data amounting to an integrated luminosity of 7.5/fb at a center of mass energy of 1.96 TeV collected at the Collider Detector at Fermilab (CDF) at the Tevatron are analyzed. Two objectives are pursued in the methods applied: maximize acceptance, and distinguish the signal from background. The first aim is met by applying... more Vladimir ManucharyanMichel Devoret Postdoctoral AssociateHarvardSuperinductance: a New Element for Quantum CircuitsWe harness the phenomenon of kinetic inductance of a superconductor for the purposes of quantum information processing with superconducting circuits. In the present work, kinetic inductance of an array of Josephson tunnel junctions with carefully chosen parameters exceeds its geometric (magnetic) inductance by four orders of magnitude. Using such inductance, one can construct electrical circuits, in which quantum electrodynamics of charges and fluxes is governed by an effective fine structure... more Carl SchreckCorey O'Hern Assoc Mech Eng & Materials SciYale UniversityMechanical and vibrational properties of model granular mediaThis thesis describes comprehensive computational and theoretical studies of the mechanical and vibrational properties of athermal particulate systems, such as granular media, foams, and emulsions, modeled as frictionless particles with spherical or ellipsoidal shapes. First, we investigate the mechanical properties of static packings of ellipsoidal particles. While amorphous packings of spherical particles are isostatic at jamming onset and possess the minimum contact number $z=z_{\rm iso}$... more Benjamin ZwicklJack Harris Assistant Professor of PhysicsRochester Institute of TechnologyProgress Toward Observation of Radiation Pressure Shot NoiseAbstract: It has been over 100 years since the first conclusive demonstration of radiation pressure by Lebedev and Nichols and Hull. Cavity optomechanical systems---high finesse optical cavities coupled to mechanical resonators---are good testing grounds for the mechanical properties of light. The system described in this dissertation is a 7 mm long cavity coupled to a 1 mm square, 50 nm thick silicon nitride membrane. Like many similar optomechanical systems, ranging from LIGO to microtoroids... more
 Rona RamosSean Barrett Graduate Services Coordinator; Lecturer PhysicsYale UniversityNovel Pulse Sequences Exploiting the Effects of Hard π-pulsesIn magnetic resonance and other spectroscopies, the strong pulses used to control coherent spin evolution are often approximated as instantaneous delta function rotations. However, small corrections to the delta function model can cause surprising departures from the conventional theory in standard multipulse NMR experiments using strong π-pulses. In this dissertation, we report the exploration of the small correction terms resulting from the finite duration of realistic pulses, however strong... more