Alumni
Kurtis Geerlings Michel Devoret 
Improving Coherence of Superconducting Qubits and ResonatorsSuperconducting qubits and resonators with quality factors exceeding 10^7 are of great interest for quantum information processing applications. The improvement of present devices necessarily involves the consideration of participation ratios, which budget the influence of each physical component in the total energy decay rate. Experiments on compact resonators in which participation ratios were varied has demonstrated the validity of this method, yielding a twofold improvement in quality... more 

Aaron Mertz Eric Dufresne 
Collective Mechanics of Epithelial CellsCell–cell and cell–matrix adhesions play essential roles in the function of tissues, yet little is known about how crosstalk between these two adhesion types regulate cells' material properties and active processes. This dissertation combines experiment and theory to reveal how colonies of cells apply forces to the extracellular matrix. Using traction force microscopy, we measure forces transmitted to the substrate by colonies of epithelial cells with strong and weak cadherin... more 

Konstantin Nesterov Yoram Alhassid 
Mesoscopic Effects in Chaotic Metallic NanoparticlesWe study electron interactions in a nanosized chaotic metallic grain with a large Thouless conductance. We use the socalled universal Hamiltonian, which describes the lowenergy physics of such a grain. The noninteracting part of this model fluctuates and is described by randommatrix theory, while its interaction terms are universal and do not fluctuate. Of particular interest are grains in the fluctuationdominated regime of pairing correlations, where the grain is so small that its single... more 

Alice Ohlson John Harris 
Investigating Parton Energy Loss with Jethadron Correlations and Jet vn at STARA stronglycoupled, deconfined state of quarks and gluons, known as the QuarkGluon Plasma (QGP), is created in highenergy collisions of heavy nuclei. The QGP can be probed by highmomentum quarks and gluons (collectively known as partons) that are produced in hard scatterings early in the collision. The partons traverse the QGP and fragment into collimated "jets" of hadrons. Studies of parton energy loss within the QGP, or mediuminduced jet quenching, can lead to insights into the... more 

Kinga Partyka Bonnie Fleming 
Exclusive MuonNeutrino Charged Current mu+Np topologies in ArgoNeuTNeutrinos 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 bubblelike 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 Thierry Emonet 
The Molecular Origins and Functional Role of Noise in a Simple Sensory NetworkBiological pathways perform calculations with oftensmall 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 Robert Schoelkopf 
Entanglement and Quantum Error Correction with Superconducting QubitsA 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 microwavefrequency transmission line resonator which serves... more 

Charles Riley Jack Sandweiss 
Searching for Local Parity Violation in Heavy Ion CollisionsParity 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 parityodd domains in QCD are the consequence of topologically nontrivial 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 Michel Devoret 
A Practical QuantumLimited Parametric Amplifier Based on the Josephson Ring ModulatorThis dissertation has addressed the problem of developing the Josephson Parametric Converter (JPC) as a practical phasepreserving 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 trilinear form XYZ... more 

Adam Sears Robert Schoelkopf 
Extending Coherence of Superconducting Qubits: from microseconds to millisecondsCircuit 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 
Sourpouhi Bedikian Sarah Demers 
A Search for the Charged Higgs: Using Tau Polarimetry with ProtonProton Collisions at the ATLAS DetectorA 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 loglikelihood template fit. The dataset corresponds to an integrated luminosity of 4.6 fb^−1 of sqrt(s)=7 TeV protonproton collisions collected with the ATLAS detector in... more 

Christopher Gilbreth Yoram Alhassid 
Ultracold Fermi Gases: Effective Interactions and SuperfluidityCold atomic Fermi gases are clean, highly experimentally tunable systems with connections to many different fields of physics. However, in the stronglyinteracting regime they are nonperturbative and difficult to study theoretically. One challenge is to calculate the energy spectra of fewbody cold atom systems along the crossover from a gas described by a BoseEinstein condensate (BEC) to a gas described by BardeenCooperSchrieffer (BCS) theory. The configurationinteraction (CI) method is... more 

Archana Kamal Michel Devoret 
Nonreciprocity in active Josephson junction circuitsI will present different flavors of nonreciprocal photon dynamics realized using active parametric circuits based on Josephson junctions. The motivation stems from developing nonmagnetic alternatives to existing nonreciprocal devices, invariably employing magnetic materials and fields and hence limited in their application potential for use with onchip microwave superconducting circuits. The main idea rests on the fact the “pump” wave (or the carrier) in an active nonlinear system... more 

Zuhair Khandker Walter Goldberger 
Embedding Methods for Conformal Field TheorConformal 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 nonsupersymmetric setting, the embeddingspace formalism for CFTs has proven to be... more 

Nicholas Masluk Michel Devoret 
Purifying 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 Cooperpair 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 