Bulletin of the American Physical Society
2020 Annual Meeting of the APS Four Corners Section (Virtual)
Volume 65, Number 16
Friday–Saturday, October 23–24, 2020; Albuquerque, NM (Virtual)
Session J01: Quantum Information IILive
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Chair: Elizabeth Crosson, UNM |
Saturday, October 24, 2020 8:00AM - 8:24AM Live |
J01.00001: The sign problem and its relation to the spectral gap of quantum many-body systems Invited Speaker: Elizabeth Crosson The partition function of a quantum system without a sign problem can be represented by a path integral in which every amplitude is efficiently computable and nonnegative, which is a substantial simplification from the interference of complex amplitudes in the general quantum case. In quantum annealing the presence of a sign problem has at times been sought as a virtue, because it helps to increase the complexity of the quantum system beyond the range of classical simulation. In this work we propose a "de-signing" operation for adiabatic optimization, which removes the sign problem from a Hamiltonian path, and we use methods including random matrix theory, spectral graph theory, and numerical simulation to argue that this de-signing operation tends to increase the spectral gap with high probability. [Preview Abstract] |
Saturday, October 24, 2020 8:24AM - 8:36AM Live |
J01.00002: Scaling Symmetries and Conservation Laws in Fractional Quantum Mechanics Joel Been Continuity equations allow us to write local conservation laws that describe the evolution of physically important quantities, such as mass, energy, and momentum, in terms of fluxes. Because of Noether's theorem, we know that conservation laws are fundamentally connected to symmetry invariance; we find that this still holds in fractional systems. Specifically, we show that scaling symmetries combined with the fractional homotopy and correction operators allow the derivation of conservation laws for fractional evolution equations (FEEs). By choosing scaling families that leave the equation invariant, one may derive constants of motion of a FEE by finding their corresponding densities. These densities characterize quasi-continuity equations which have new source term that directly manifests the nonlocality of space fractional derivatives and shows that fractional derivatives force local conservation laws to become global. The quasi-continuity equation may be computed directly from densities using the fractional homotopy and correction operators. We applied these methods to describe probability transport for the space fractional Schrodinger equation which is important in quantum information processing because it describes the non-locality of connected systems. [Preview Abstract] |
Saturday, October 24, 2020 8:36AM - 8:48AM Live |
J01.00003: Qubit Quantum Metrology in the Regime of Limited Resources Jason Saunders, Jean-Francois Van Huele It has been demonstrated that quantum effects, such as entanglement and squeezing, can decrease the uncertainty of parameter estimation. A tight lower bound for this uncertainty exists for the regime of asymptotic measurement resources. Several bounds have been proposed for the more realistic non-asymptotic regime, but none are tight. We numerically investigate the non-asymptotic regime for a specific system: using $\nu$ qubit probes to estimate a rotation angle externally induced on the probes. We introduce a Bayesian modeling framework for qubit quantum metrology. We investigate the effect of entanglement on parameter estimation uncertainty as a function of $\nu$ in the non-asymptotic regime. [Preview Abstract] |
Saturday, October 24, 2020 8:48AM - 9:00AM Live |
J01.00004: Quantum Optimal Control of Nuclear Spin for Quantum Logic with Qudits Sivaprasad Omanakuttan, Anupam Mitra, Ivan Deutsch Quantum optimal control is a powerful tool for the robust realization of quantum information processing tasks such as preparation of nonclassical quantum states and implementation of unitary maps. We studied quantum optimal control of the the spin I=9/2 nucleus of 87Sr, an alkaline earth atom that has attracted substantial recent attention for metrology, quantum simulation and quantum computing. By employing nuclear spin magnetic resonance in the presence of a laser-induced nonlinear AC Stark shift, the system is controllable; we can design any SU(10) unitary matrix acting on the d=10 dimensional manifold of nuclear magnetic sublevels. We design control waveforms that generate the fundamental gates required for universal qudit logic gates. We also study experimental trade-offs including the affects of decoherence and robustness to imperfections. [Preview Abstract] |
Saturday, October 24, 2020 9:00AM - 9:12AM Live |
J01.00005: A machine learned model for quick access to analytic solutions of a QIS system Salvador Sosa Guitron, Aasma Aslam, Trudy Bolin, Kevin Brown, Clio Gonzalez-Zacarias, Bohong Huang, Salvador Sosa For quantum information ion systems, the calculation of analytic solutions describing a state of interest can become computationally expensive even for systems with a relatively small number of ions. This can become a big constriction when attempting to quickly access specific states of a quantum ion system for manipulation. Here we describe the implementation of a Machine Learning algorithm to determine the equilibrium positions of a linear chain of ions, an ideal configuration of ions in a Paul trap or a storage ring with a crystalline beam. Specifically, given the solutions of this system for a relatively small amount of ions, our ML predicts the partial equilibrium solution of the system with a higher number of ions where the numerical approach takes longer calculating time with increasing number of ions. [Preview Abstract] |
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