Results for "Jay M. Gambetta"

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Building logical qubits in a superconducting quantum computing systemOct 15 2015The technological world is in the midst of a quantum computing and quantum information revolution. Since Richard Feynman's famous "plenty of room at the bottom" lecture, hinting at the notion of novel devices employing quantum mechanics, the quantum information ... More
Rapid Driven Reset of a Qubit Readout ResonatorMar 04 2015May 22 2015Using a circuit QED device, we demonstrate a simple qubit measurement pulse shape that yields fast ring-up and ring-down of the readout resonator regardless of the qubit state. The pulse differs from a square pulse only by the inclusion of additional ... More
Reducing Spontaneous Emission in Circuit Quantum Electrodynamics by a Combined Readout/Filter TechniqueApr 16 2015Oct 20 2015Physical implementations of qubits can be extremely sensitive to environmental coupling, which can result in decoherence. While efforts are made for protection, coupling to the environment is necessary to measure and manipulate the state of the qubit. ... More
Characterizing errors on qubit operations via iterative randomized benchmarkingApr 24 2015With improved gate calibrations reducing unitary errors, we achieve a benchmarked single-qubit gate fidelity of 99.95% with superconducting qubits in a circuit quantum electrodynamics system. We present a method for distinguishing between unitary and ... More
Validating quantum computers using randomized model circuitsNov 30 2018We introduce a single-number metric, quantum volume, that can be measured using a concrete protocol on near-term quantum computers of modest size ($n\lesssim 50$), and measure it on several state-of-the-art transmon devices, finding values as high as ... More
Open Quantum Assembly LanguageJul 11 2017Jul 13 2017This document describes a quantum assembly language (QASM) called OpenQASM that is used to implement experiments with low depth quantum circuits. OpenQASM represents universal physical circuits over the CNOT plus SU(2) basis with straight-line code that ... More
Scalable randomized benchmarking of non-Clifford gatesOct 09 2015Randomized benchmarking is a widely used experimental technique to characterize the average error of quantum operations. Benchmarking procedures that scale to enable characterization of $n$-qubit circuits rely on efficient procedures for manipulating ... More
Self-Consistent Quantum Process TomographyNov 01 2012Quantum process tomography is a necessary tool for verifying quantum gates and diagnosing faults in architectures and gate design. We show that the standard approach of process tomography is grossly inaccurate in the case where the states and measurement ... More
Tomography via Correlation of Noisy Measurement RecordsOct 24 2013Dec 20 2013We present methods and results of shot-by-shot correlation of noisy measurements to extract entangled state and process tomography in a superconducting qubit architecture. We show that averaging continuous values, rather than counting discrete thresholded ... More
Demonstration of quantum advantage in machine learningDec 18 2015The main promise of quantum computing is to efficiently solve certain problems that are prohibitively expensive for a classical computer. Most problems with a proven quantum advantage involve the repeated use of a black box, or oracle, whose structure ... More
Verifying Multipartite Entangled GHZ States via Multiple Quantum CoherencesMay 14 2019The ability to generate and verify multipartite entanglement is an important benchmark for near-term quantum devices devices. We develop a scalable entanglement metric based on multiple quantum coherences, and demonstrate experimentally on a 20-qubit ... More
Characterization of addressability by simultaneous randomized benchmarkingApr 27 2012Jan 02 2013The control and handling of errors arising from cross-talk and unwanted interactions in multi-qubit systems is an important issue in quantum information processing architectures. We introduce a benchmarking protocol that provides information about the ... More
A simple all-microwave entangling gate for fixed-frequency superconducting qubitsJun 03 2011We demonstrate an all-microwave two-qubit gate on superconducting qubits which are fixed in frequency at optimal bias points. The gate requires no additional subcircuitry and is tunable via the amplitude of microwave irradiation on one qubit at the transition ... More
Efficient measurement of quantum gate error by interleaved randomized benchmarkingMar 20 2012Mar 19 2014We describe a scalable experimental protocol for obtaining estimates of the error rate of individual quantum computational gates. This protocol, in which random Clifford gates are interleaved between a gate of interest, provides a bounded estimate of ... More
Exploring non-equilibrium phases of the generalized Dicke model with a trapped Rydberg ion quantum simulatorFeb 28 2019Trapped ions are a versatile platform for the investigation of quantum many-body phenomena, in particular for the study of scenarios where long-range interactions are mediated by phonons. Recent experiments have shown that the trapped ion platform can ... More
Dispersive regime of circuit QED: photon-dependent qubit dephasing and relaxation ratesOct 08 2008Oct 24 2008Superconducting electrical circuits can be used to study the physics of cavity quantum electrodynamics (QED) in new regimes, therefore realizing circuit QED. For quantum information processing and quantum optics, an interesting regime of circuit QED is ... More
Non-linear dispersive regime of cavity QED: The dressed dephasing modelMar 03 2008Jun 17 2008Systems in the dispersive regime of cavity quantum electrodynamics (QED) are approaching the limits of validity of the dispersive approximation. We present a model which takes into account nonlinear corrections to the dressing of the atom by the field. ... More
Non-Markovian stochastic Schrödinger equations: Generalization to real-valued noise using quantum measurement theoryFeb 20 2002Apr 14 2007Do stochastic Schr\"odinger equations, also known as unravelings, have a physical interpretation? In the Markovian limit, where the system {\em on average} obeys a master equation, the answer is yes. Markovian stochastic Schr\"odinger equations generate ... More
The interpretation of non-Markovian stochastic Schrödinger equations as a hidden-variable theoryJul 10 2003Apr 14 2007Do diffusive non-Markovian stochastic Schr\"odinger equations (SSEs) for open quantum systems have a physical interpretation? In a recent paper [Phys. Rev. A 66, 012108 (2002)] we investigated this question using the orthodox interpretation of quantum ... More
State and dynamical parameter estimation for open quantum systemsMar 08 2001Apr 14 2007Following the evolution of an open quantum system requires full knowledge of its dynamics. In this paper we consider open quantum systems for which the Hamiltonian is ``uncertain''. In particular, we treat in detail a simple system similar to that considered ... More
Stochastic simulations of conditional states of partially observed systems, quantum and classicalMar 31 2005Apr 06 2007In a partially observed quantum or classical system the information that we cannot access results in our description of the system becoming mixed even if we have perfect initial knowledge. That is, if the system is quantum the conditional state will be ... More
A perturbative approach to non-Markovian stochastic Schrödinger equationsAug 28 2002Apr 14 2007In this paper we present a perturbative procedure that allows one to numerically solve diffusive non-Markovian Stochastic Schr\"odinger equations, for a wide range of memory functions. To illustrate this procedure numerical results are presented for a ... More
The non-Markovian stochastic Schrödinger equation for the position unravelingMay 09 2003Apr 14 2007An important and well established area of quantum optics is the theory of Markovian stochastic Schr\"odinger equations (or by another name quantum trajectory theory). Recently stochastic Schr\"odinger equations have been developed for non-Markovian systems. ... More
Effective Hamiltonian models of the cross-resonance gateApr 11 2018Feb 25 2019Effective Hamiltonian methods are utilized to model the two-qubit cross-resonance gate for both the ideal two-qubit case and when higher levels are included. Analytic expressions are obtained in the qubit case and the higher-level model is solved both ... More
Modal dynamics for positive operator measuresJun 21 2003Apr 06 2007The modal interpretation of quantum mechanics allows one to keep the standard classical definition of realism intact. That is, variables have a definite status for all time and a measurement only tells us which value it had. However, at present modal ... More
Pre-Hausdorff SpacesMar 07 2008This paper introduces three separation conditions for topological spaces, called T_{0,1}, T_{0,2} ("pre-Hausdorff"), and T_{1,2}. These conditions generalize the classical T_(1) and T_(2) separation axioms, and they have advantages over them topologically ... More
Are dynamical quantum jumps detector-dependent?Oct 01 2011Apr 19 2012Dynamical quantum jumps were initially conceived by Bohr as objective events associated with the emission of a light quantum by an atom. Since the early 1990s they have come to be understood as being associated rather with the detection of a photon by ... More
Characterizing Quantum Gates via Randomized BenchmarkingSep 30 2011Apr 27 2012We describe and expand upon the scalable randomized benchmarking protocol proposed in Phys. Rev. Lett. 106, 180504 (2011) which provides a method for benchmarking quantum gates and estimating the gate-dependence of the noise. The protocol allows the noise ... More
Dynamical parameter estimation using realistic photodetectionJan 13 2004Apr 14 2007We investigate the effect of imperfections in realistic detectors upon the problem of quantum state and parameter estimation by continuous monitoring of an open quantum system. Specifically, we have reexamined the system of a two-level atom with an unknown ... More
Error mitigation for short depth quantum circuitsDec 06 2016Two schemes are presented that mitigate the effect of errors and decoherence in short depth quantum circuits. The size of the circuits for which these techniques can be applied is limited by the rate at which the errors in the computation are introduced. ... More
Jump-like unravelings for non-Markovian open quantum systemsJan 27 2004Apr 06 2007Non-Markovian evolution of an open quantum system can be `unraveled' into pure state trajectories generated by a non-Markovian stochastic (diffusive) Schr\"odinger equation, as introduced by Di\'osi, Gisin, and Strunz. Recently we have shown that such ... More
Optimized pulse shapes for a resonator-induced phase gateNov 20 2014Apr 06 2015The resonator-induced phase gate is a multi-qubit controlled-phase gate for fixed-frequency superconducting qubits. Through off-resonant driving of a bus resonator, statically coupled qubits acquire a state-dependent phase. However, photon loss leads ... More
Quantification and Characterization of Leakage ErrorsApr 10 2017We present a general framework for the quantification and characterization of leakage errors that result when a quantum system is encoded in the subspace of a larger system. To do this we introduce new metrics for quantifying the coherent and incoherent ... More
Procedure for systematically tuning up crosstalk in the cross resonance gateMar 15 2016We present improvements in both theoretical understanding and experimental implementation of the cross resonance (CR) gate that have led to shorter two-qubit gate times and interleaved randomized benchmarking fidelities exceeding 99%. The CR gate is an ... More
Detector dependency of diffusive quantum monitoringsMay 01 2015Continuous measurements play a pivotal role in the study of dynamical open quantum systems. `Dyne' detections are among the most widespread and efficient measurement schemes, and give rise to quantum diffusion of the conditioned state. In this work we ... More
Purcell effect with microwave drive: Suppression of qubit relaxation rateJan 22 2014Mar 21 2014We analyze the Purcell relaxation rate of a superconducting qubit coupled to a resonator, which is coupled to a transmission line and pumped by an external microwave drive. Considering the typical regime of the qubit measurement, we focus on the case ... More
Model for monitoring of a charge qubit using a radio-frequency quantum point contact including experimental imperfectionsJun 24 2007Mar 06 2008The extension of quantum trajectory theory to incorporate realistic imperfections in the measurement of solid-state qubits is important for quantum computation, particularly for the purposes of state preparation and error-correction as well as for readout ... More
Maximum Likelihood, Minimum EffortJun 27 2011Sep 07 2011We provide an efficient method for computing the maximum likelihood mixed quantum state (with density matrix rho) given a set of measurement outcome in a complete orthonormal operator basis subject to Gaussian noise. Our method works by first changing ... More
Josephson junction-embedded transmission-line resonators: from Kerr medium to in-line transmonApr 10 2012Jul 17 2012We provide a general method to find the Hamiltonian of a linear circuit in the presence of a nonlinearity. Focussing on the case of a Josephson junction embedded in a transmission-line resonator, we solve for the normal modes of the system by taking into ... More
Leakage Suppression in the Toric CodeOct 30 2014Quantum codes excel at correcting local noise but fail to correct leakage faults that excite qubits to states outside the computational space. Aliferis and Terhal have shown that an accuracy threshold exists for leakage faults using gadgets called leakage ... More
Anomalies and fluctuations of near-surface air temperature at Tianhuangping (Zhejiang), China, produced by the longest total solar eclipse of the 21st century under cloudy skiesMay 09 2019We analyze the near-surface air temperature response, at three different heights over the ground, recorded by the Williams College expedition under meteorological conditions characterized by cloudy skies during the longest total solar eclipse of the 21st ... More
Inclusion properties for bi-univalent functions of complex order defined by combining of Faber polynomial expansions and Fibonacci numbersJan 13 2019In this present investigation, we introduce the new class R of bi-univalent functions defined by using the Tremblay fractional derivative operator. Additionally, we use the Faber polynomial expansions and Fibonacci numbers to derive bounds for the general ... More
A Point Process Model for Generating Biofilms with Realistic Microstructure and RheologyJul 16 2017Biofilms are communities of bacteria that exhibit a multitude of multiscale biomechanical behaviors. Recent experimental advances have lead to characterizations of these behaviors in terms of measurements of the viscoelastic moduli of biofilms grown in ... More
Far-Ultraviolet Spectroscopy of Star-Forming Regions in Nearby Galaxies: Stellar Populations and Abundance IndicatorsMar 20 2004We present FUSE spectroscopy and supporting data for star-forming regions in nearby galaxies, to examine their massive-star content and explore the use of abundance and population indicators in this spectral range for high-redshift galaxies. New far-ultraviolet ... More
How super-tough gels breakAug 23 2018Fracture of highly stretched materials challenges our view of how things break. We directly visualize rupture of tough double-network (DN) gels at >50\% strain. During fracture, crack tip shapes obey a $x\sim y^{1.6}$ power-law, in contrast to the parabolic ... More
Analytic control methods for high fidelity unitary operations in a weakly nonlinear oscillatorNov 09 2010Jan 20 2011In qubits made from a weakly anharmonic oscillator the leading source of error at short gate times is leakage of population out of the two dimensional Hilbert space that forms the qubit. In this paper we develop a general scheme based on an adiabatic ... More
Limb Spicules from the Ground and from SpaceAug 31 2009We amassed statistics for quiet-sun chromosphere spicules at the limb using ground-based observations from the Swedish 1-m Solar Telescope on La Palma and simultaneously from NASA's Transition Region and Coronal Explorer (TRACE) spacecraft. The observations ... More
Crack-Like Processes Governing the Onset of Frictional SlipMar 20 2006We perform real-time measurements of the net contact area between two blocks of like material at the onset of frictional slip. We show that the process of interface detachment, which immediately precedes the inception of frictional sliding, is governed ... More
Induced Characters of Type D Weyl Groups and the Littlewood-Richardson RuleAug 18 2014Nov 04 2014For any ordinary irreducible character of a maximal reflection subgroup of type $D_aD_b$ of a type $D$ Weyl group we give an explicit decomposition of the induced character in terms of Littlewood-Richardson coefficients.
Evaluating Characteristic Functions of Character Sheaves at Unipotent ElementsMar 29 2014Sep 16 2014Assume $\mathbf{G}$ is a connected reductive algebraic group defined over an algebraic closure $\mathbb{K} = \overline{\mathbb{F}}_p$ of the finite field of prime order $p>0$. Furthermore, assume that $F : \mathbf{G} \to \mathbf{G}$ is a Frobenius endomorphism ... More
Lectures on Isomorphism TheoremsJul 07 2014These notes originated in a series of lectures I gave in Marseille in May, 2013. I was invited to give an introduction to the isomorphism theorems, originating with Dynkin, which connect Markov local times and Gaussian processes. This is an area I had ... More
Virtual Resolutions of Monomial Ideals on Toric VarietiesJun 03 2019We use cellular resolutions of monomial ideals to prove an analog of Hilbert's syzygy theorem for virtual resolutions of monomial ideals on smooth toric varieties.
Universality of the Pinch Technique Gauge Boson Self-EnergiesDec 19 1994Jun 23 1995It is shown how the S-matrix pinch technique may be extended to the cases of external scalar and gauge boson fields. Using this extension, the universality of the pinch technique gauge-independent one-loop gauge boson self-energy in a general unbroken ... More
Several Convex-Ear DecompositionsMay 09 2006In this paper we give convex-ear decompositions for the order complexes of several classes of posets, namely supersolvable lattices with non-zero Mobius functions and rank-selected subposets of such lattices, rank-selected geometric lattices, and rank-selected ... More
Microwave-activated conditional-phase gate for superconducting qubitsJul 09 2013We introduce a new entangling gate between two fixed-frequency qubits statically coupled via a microwave resonator bus which combines the following desirable qualities: all-microwave control, appreciable qubit separation for reduction of crosstalk and ... More
Action of Automorphisms on Irreducible Characters of Symplectic GroupsDec 09 2016Assume $G$ is a finite symplectic group $\mathrm{Sp}_{2n}(q)$ over a finite field $\mathbb{F}_q$ of odd characteristic. We describe the action of the automorphism group $\mathrm{Aut}(G)$ on the set $\mathrm{Irr}(G)$ of ordinary irreducible characters ... More
Intersection local times for interlacementsAug 15 2013Jan 08 2014We define renormalized intersection local times for random interlacements of L\'evy processes in R^{d} and prove an isomorphism theorem relating renormalized intersection local times with associated Wick polynomials.
Efficient Z-Gates for Quantum ComputingDec 02 2016For superconducting qubits, microwave pulses drive rotations around the Bloch sphere. Here we show that the phase of these drives can be used to generate zero-duration arbitrary Z-gates which, combined with two $X_{\pi/2}$ gates, can generate any SU(2) ... More
Extending the computational reach of a noisy superconducting quantum processorMay 11 2018Quantum computation, a completely different paradigm of computing, benefits from theoretically proven speed-ups for certain problems and opens up the possibility of exactly studying the properties of quantum systems. Yet, because of the inherent fragile ... More
Investigating the limits of randomized benchmarking protocolsAug 13 2013In this paper, we analyze the performance of randomized benchmarking protocols on gate sets under a variety of realistic error models that include systematic rotations, amplitude damping, leakage to higher levels, and 1/f noise. We find that, in almost ... More
Experimental demonstration of fault-tolerant state preparation with superconducting qubitsMay 25 2017Robust quantum computation requires encoding delicate quantum information into degrees of freedom that are hard for the environment to change. Quantum encodings have been demonstrated in many physical systems by observing and correcting storage errors, ... More
The Asymptotic Number of Simple Singular Vector Tuples of a Cubical TensorMay 19 2016Jul 12 2016S. Ekhad and D. Zeilberger recently proved that the multivariate generating function for the number of simple singular vector tuples of a generic $m_1 \times \cdots \times m_d$ tensor has an elegant rational form involving elementary symmetric functions, ... More
Solution of the SU(2) Mandelstam ConstraintsNov 22 1993It is shown how the Mandelstam constraints for an $SU(2)$ pure lattice gauge theory with $3{\cal N}$ physical degrees of freedom may be solved completely in terms of $3{\cal N}$ Wilson and Polyakov loop variables and ${\cal N}-1$ gauge invariant discrete ... More
Generalised Gelfand-Graev Representations in Small CharacteristicsAug 07 2014Sep 14 2015Let $\mathbf{G}$ be a connected reductive algebraic group over an algebraic closure $\overline{\mathbb{F}_p}$ of the finite field of prime order $p$ and let $F : \mathbf{G} \to \mathbf{G}$ be a Frobenius endomorphism with $G = \mathbf{G}^F$ the corresponding ... More
A random walk proof of the Erdos-Taylor conjectureMar 06 2005For the simple random walk in Z^2 we study those points which are visited an unusually large number of times, and provide a new proof of the Erdos-Taylor conjecture describing the number of visits to the most visited point.
A CLT for the third integrated moment of Brownian local time incrementsJul 15 2009Oct 20 2009Let $\{L^{x}_{t} ; (x,t)\in R^{1}\times R^{1}_{+}\}$ denote the local time of Brownian motion. Our main result is to show that for each fixed $t$ $${\int (L^{x+h}_t- L^x_t)^3 dx-12h\int (L^{x+h}_t - L^x_t)L^x_t dx-24h^{2}t\over h^2} \stackrel{\mathcal{L}}{\Longrightarrow}\sqrt{192}(\int ... More
The Structure of Root Data and Smooth Regular Embeddings of Reductive GroupsOct 16 2017Mar 09 2018We investigate the structure of root data by considering their decomposition as a product of a semisimple root datum and a torus. Using this decomposition we obtain a parameterisation of the isomorphism classes of all root data. By working at the level ... More
Mermin inequalities for perfect correlations in many-qutrit systemsJan 28 2017Jul 27 2017The existence of GHZ contradictions in many-qutrit systems was a long-standing theoretical question until it's (affirmative) resolution in 2013. To enable experimental tests, we derive Mermin inequalities from concurrent observable sets identified in ... More
A universal gate for fixed-frequency qubits via a tunable busApr 11 2016Aug 18 2016A challenge for constructing large circuits of superconducting qubits is to balance addressability, coherence and coupling strength. High coherence can be attained by building circuits from fixed-frequency qubits, however, leading techniques cannot couple ... More
A universal gate for fixed-frequency qubits via a tunable busApr 11 2016Dec 19 2016A challenge for constructing large circuits of superconducting qubits is to balance addressability, coherence and coupling strength. High coherence can be attained by building circuits from fixed-frequency qubits, however, leading techniques cannot couple ... More
Three Qubit Randomized BenchmarkingDec 18 2017Dec 12 2018As quantum circuits increase in size, it is critical to establish scalable multiqubit fidelity metrics. Here we investigate three-qubit randomized benchmarking (RB) with fixed-frequency transmon qubits coupled to a common bus with pairwise microwave-activated ... More
Quantum trajectory approach to circuit QED: Quantum jumps and the Zeno effectSep 26 2007Jan 25 2008We present a theoretical study of a superconducting charge qubit dispersively coupled to a transmission line resonator. Starting from a master equation description of this coupled system and using a polaron transformation, we obtain an exact effective ... More
Machine learning for discriminating quantum measurement trajectories and improving readoutNov 18 2014Nov 24 2014High-fidelity measurements are important for the physical implementation of quantum information protocols. Current methods for classifying measurement trajectories in superconducting qubit systems produce fidelities that are systematically lower than ... More
Efficient Z-Gates for Quantum ComputingDec 02 2016Jun 28 2017For superconducting qubits, microwave pulses drive rotations around the Bloch sphere. The phase of these drives can be used to generate zero-duration arbitrary "virtual" Z-gates which, combined with two $X_{\pi/2}$ gates, can generate any SU(2) gate. ... More
Characterization of hidden modes in networks of superconducting qubitsMar 13 2017Dec 05 2017We present a method for detecting electromagnetic (EM) modes that couple to a superconducting qubit in a circuit-QED architecture. Based on measurement-induced dephasing, this technique allows the measurement of modes that have a high quality factor (Q) ... More
Analytical determination of participation in superconducting coplanar architecturesDec 14 2017Jun 18 2018Superconducting qubits are sensitive to a variety of loss mechanisms which include dielectric loss from interfaces. The calculation of participation near the key interfaces of planar designs can be accomplished through an analytical description of the ... More
High Fidelity Quantum Gates in the Presence of DispersionNov 07 2011We numerically demonstrate the control of motional degrees of freedom of an ensemble of neutral atoms in an optical lattice with a shallow trapping potential. Taking into account the range of quasimomenta across different Brillouin zones results in an ... More
Coherent Control of a Superconducting Qubit with Dynamically Tunable Qubit-cavity CouplingAug 12 2011We demonstrate coherent control and measurement of a superconducting qubit coupled to a superconducting coplanar waveguide resonator with a dynamically tunable qubit-cavity coupling strength. Rabi oscillations are measured for several coupling strengths ... More
Effective Theories of Flavor and the Non-Universal MSSMJul 22 2016Flavor symmetries \`a la Froggatt-Nielsen~(FN) provide a compelling way to explain the hierarchies of fermionic masses and mixing angles in the Yukawa sector. In Supersymmetric (SUSY) extensions of the Standard Model where the mediation of SUSY breaking ... More
Protocols for optimal readout of qubits using a continuous quantum nondemolition measurementJan 04 2007Dec 24 2007We study how the spontaneous relaxation of a qubit affects a continuous quantum non-demolition measurement of the initial state of the qubit. Given some noisy measurement record $\Psi$, we seek an estimate of whether the qubit was initially in the ground ... More
Aeolus: A Markov--Chain Monte Carlo code for mapping ultracool atmospheres. An application on Jupiter and brown dwarf HST light curvesOct 14 2015Deducing the cloud cover and its temporal evolution from the observed planetary spectra and phase curves can give us major insight into the atmospheric dynamics. In this paper, we present Aeolus, a Markov-Chain Monte Carlo code that maps the structure ... More
Radiative contribution to the effective potential in composite Higgs models from lattice gauge theoryJun 08 2016Aug 14 2016We develop methods to calculate the electroweak gauge boson contribution to the effective Higgs potential in the context of composite Higgs models, using lattice gauge theory. The calculation is analogous to that of the electromagnetic mass splitting ... More
Benchmarking conductivity predictions of the Advanced Electrolyte Model (AEM) for aqueous systemsJun 14 2019High-concentration aqueous electrolytes have shown promise as candidates for a safer, lower-cost battery system. Ionic conductivity is a key property required in high performing electrolytes; the Advanced Electrolyte Model (AEM) has previously shown great ... More
A Deep Multiwavelength View of Binaries in Omega CentauriDec 16 2010We summarize results of a search for X-ray-emitting binary stars in the massive globular cluster Omega Centauri (NGC 5139) using Chandra and HST. ACIS-I imaging reveals 180 X-ray sources, of which we estimate that 45-70 are associated with the cluster. ... More
The White Dwarfs within 20 Parsecs of the Sun: Kinematics and StatisticsOct 07 2009Oct 08 2009We present the kinematical properties, distribution of spectroscopic subtypes, stellar population subcomponents of the white dwarfs within 20 pc of the sun. We find no convincing evidence of halo white dwarfs in the total 20 pc sample of 129 white dwarfs ... More
Radiative contribution to the effective potential in a composite Higgs modelOct 19 2016The SU(4) gauge theory with two flavors of Dirac fermions in the sextet representation shares features of a candidate for a composite Higgs model. The analogue of the Higgs multiplet of the Standard Model lives in the Goldstone manifold resulting from ... More
Non-monotonic diffusion rates in atom-optics Lévy kicked rotorApr 29 2019May 06 2019The dynamics of chaotic Hamiltonian systems such as the kicked rotor continues to guide our understanding of transport and localization processes. The localized states of the quantum kicked rotor decay due to decoherence effects if subjected to stationary ... More
A $q$-Analogue of $r$-Whitney Numbers of the Second Kind and Its Hankel TransformJul 06 2019Jul 23 2019A $q$-analogue of $r$-Whitney numbers of the second kind, denoted by $W_{m,r}[n,k]_q$, is defined by means of a triangular recurrence relation. In this paper, several fundamental properties for the $q$-analogue are established including other forms of ... More
Randomized benchmarking and process tomography for gate errors in a solid-state qubitNov 26 2008We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pi pulse experiment. Randomized benchmarking reveals ... More
Detecting arbitrary quantum errors via stabilizer measurements on a sublattice of the surface codeOct 23 2014To build a fault-tolerant quantum computer, it is necessary to implement a quantum error correcting code. Such codes rely on the ability to extract information about the quantum error syndrome while not destroying the quantum information encoded in the ... More
Quantum information processing with circuit quantum electrodynamicsDec 01 2006Jun 01 2007We theoretically study single and two-qubit dynamics in the circuit QED architecture. We focus on the current experimental design [Wallraff et al., Nature 431, 162 (2004); Schuster et al., Nature 445, 515 (2007)] in which superconducting charge qubits ... More
Demonstration of weight-four parity measurements in the surface code architectureMay 04 2016Apr 28 2017We present parity measurements on a five-qubit lattice with connectivity amenable to the surface code quantum error correction architecture. Using all-microwave controls of superconducting qubits coupled via resonators, we encode the parities of four ... More
Cross-resonance interactions between superconducting qubits with variable detuningMay 27 2019Cross-resonance interactions are a promising way to implement all-microwave two-qubit gates with fixed-frequency qubits. In this work, we study the dependence of the cross-resonance interaction rate on qubit-qubit detuning and compare with a model that ... More
Bulk and surface loss in superconducting transmon qubitsSep 13 2015Decoherence of superconducting transmon qubits is purported to be consistent with surface loss from two-level systems on the substrate surface. Here, we present a study of surface loss in transmon devices, explicitly designed to have varying sensitivities ... More
Demonstration of weight-four parity measurements in the surface code architectureMay 04 2016May 05 2016We present parity measurements on a five-qubit lattice with connectivity amenable to the surface code quantum error correction architecture. Using all-microwave controls of superconducting qubits coupled via resonators, we encode the parities of four ... More
Broadband Filters for Abatement of Spontaneous Emission in Circuit Quantum ElectrodynamicsAug 07 2015Oct 29 2015The ability to perform fast, high-fidelity readout of quantum bits (qubits) is essential to the goal of building a quantum computer. However, coupling a fast measurement channel to a superconducting qubit typically also speeds up its relaxation via spontaneous ... More
Supervised learning with quantum enhanced feature spacesApr 30 2018Jun 05 2018Machine learning and quantum computing are two technologies each with the potential for altering how computation is performed to address previously untenable problems. Kernel methods for machine learning are ubiquitous for pattern recognition, with support ... More
Characterizing a Four-Qubit Planar Lattice for Arbitrary Error DetectionSep 09 2015Quantum error correction will be a necessary component towards realizing scalable quantum computers with physical qubits. Theoretically, it is possible to perform arbitrarily long computations if the error rate is below a threshold value. The two-dimensional ... More
Evidence that self-similar microrheology of highly entangled polymeric solutions scales robustly with, and is tunable by, polymer concentrationOct 15 2018We report observations of a remarkable scaling behavior with respect to concentration in the passive microbead rheology of two highly entangled polymeric solutions, polyethylene oxide (PEO) and hyaluronic acid (HA). This behavior was reported previously ... More
A (2n+1)-dimensional quantum group constructed from a skew-symmetric matrixJun 09 2011Beginning with a skew-symmetric matrix, we define a certain Poisson--Lie group. Its Poisson bracket can be viewed as a cocycle perturbation of the linear (or "Lie-Poisson") Poisson bracket. By analyzing this Poisson structure, we gather enough information ... More