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Lower Bound on the Entropy of Boundaries and Junctions in ( 1 + 1 )-Dimensional Quantum Critical Systems
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Crossover Physics in the Nonequilibrium Dynamics of Quenched Quantum Impurity Systems
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Symmetry Breaking Bias and the Dynamics of a Quantum Phase Transition
The Kibble-Zurek mechanism predicts the formation of topological defects and other excitations that quantify how much a quantum system driven across a quantum critical point fails to be adiabatic. We point out that, thanks to the divergent linear susceptibility at the critical point, even a tiny symmetry breaking bias can restore the adiabaticity. Furthermore, the minimal required bias scales like τ Q - β δ / ( 1 + z ν ) , where β , δ , z , ν are the critical exponents and τ Q is a quench time. We test this prediction by DMRG simulations of the quantum Ising chain. It is directly applicable to the recent emulation of quantum phase transition dynamics in the Ising chain with ultracold Rydberg atoms.
High-Fidelity Software-Defined Quantum Logic on a Superconducting Qudit
We present an efficient approach to achieving arbitrary, high-fidelity control of a multilevel quantum system using optimal control techniques. As an demonstration, we implement a continuous, software-defined microwave pulse to realize a 0 ↔ 2 SWAP gate that achieves an average gate fidelity of 99.4%. We describe our procedure for extracting the system Hamiltonian, calibrating the quantum and classical hardware chain, and evaluating the gate fidelity. Our work represents an alternative, fully generalizable route towards achieving universal quantum control by leveraging optimal control techniques.
Effective field theory for fractional quantum Hall systems near ν = 5 / 2
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Complexity of Quantum State Verification in the Quantum Linear Systems Problem
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Quantum Computer Systems for Scientific Discovery
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Quantum Vulnerability Analysis to Guide Robust Quantum Computing System Design
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Niobium quarter-wave resonator with the optimized shape for quantum information systems
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Misanthropic entropy and renormalization as a communication channel
A central physical question is the extent to which infrared (IR) observations are sufficient to reconstruct a candidate ultraviolet (UV) completion. We recast this question as a problem of communication, with messages encoded in field configurations of the UV being transmitted to the IR degrees of freedom via a noisy channel specified by renormalization group (RG) flow, with noise generated by coarse graining/decimation. We present an explicit formulation of these considerations in terms of lattice field theory, where we show that the “misanthropic entropy” — the mutual information obtained from decimating neighbors — encodes the extent to which information is lost in marginalizing over/tracing out UV degrees of freedom. Our considerations apply both to statistical field theories as well as density matrix renormalization of quantum systems, where in the quantum case, the statistical field theory analysis amounts to a leading-order approximation. As a concrete example, we focus on the case of the 2D Ising model, where we show that the misanthropic entropy detects the onset of the phase transition at the Ising model critical point.
qcal v0.0.1
qcal is a software package for calibration, characterization, and benchmarking of quantum gates. It was developed to operate full-stack superconducting quantum systems at the Advanced Quantum Testbed.
Sterile Neutrinos in Cold Climates
Measurements of neutrino oscillations at short baselines contain an intriguing set of experimental anomalies that may be suggestive of new physics such as the existence of sterile neutrinos. This three-part thesis presents research directed towards understanding these anomalies and searching for sterile neutrino oscillations. Part I contains a theoretical discussion of neutrino coherence properties. The open-quantum-system picture of neutrino beams, which allows a rigorous prediction of coherence distances for accelerator neutrinos, is presented. Validity of the standard treatment of active and sterile neutrino oscillations at short baselines is verified and non-standard coherence loss effects at longer baselines are predicted. Part II concerns liquid argon detector development for the MicroBooNE experiment, which will search for short-baseline oscillations in the Booster Neutrino Beam at Fermilab. Topics include characterization and installation of the MicroBooNE optical system; test-stand measurements of liquid argon optical properties with dissolved impurities; optimization of wavelength-shifting coatings for liquid argon scintillation light detection; testing and deployment of high-voltage surge arrestors to protect TPC field cages; and software development for optical and TPC simulation and reconstruction. Part III presents a search for sterile neutrinos using the IceCube neutrino telescope, which has collected a large sample of atmospheric-neutrino-induced events in the 1-10 TeV energy range. Sterile neutrinos would modify the detected neutrino flux shape via MSW-resonant oscillations. Following a careful treatment of systematic uncertainties in the sample, no evidence for MSW-resonant oscillations is observed, and exclusion limits on 3+1 model parameter space are derived. Under the mixing assumptions made, the 90\% confidence level exclusion limit extends to $\mathrm{sin}^2 2\theta_{24} \leq 0.02$ at $\Delta m^2 \sim 0.3\,eV^2$, and the LSND and MiniBooNE allowed regions are excluded at~>99\% confidence level.
Leveraging Modern SoC FPGA Capabilities to Improve the Performance, Configurability, and Maintainability of Quantum Control Systems.
Abstract not provided.
Investigation of Optimizations for FPGA-based Controls Hardware for Experiments using Superconducting Quantum Computing Systems
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Classical Machine Learning for Quantum Information Systems
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