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 M05: Quantum Information IIILive
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Chair: Jean-Francois Van Huele, Brigham Young University |
Saturday, October 24, 2020 12:30PM - 12:42PM Live |
M05.00001: Interdimensional Quantum Cloning CHAN HYUN PAK, Jean-Francois Van Huele We introduce the concept of Interdimensional Quantum Cloning (IDC). The aim of IDC is to maximize fidelity by manipulating information of input state in different dimensions. We briefly present different approaches to IDC. In particular, we investigate how to perform IDC by representing a qutrit as three qubits as proposed by Lopez-Saldivar et. al. [Quantum Information Processing 18.7 (2019): 210.] and applying universal quantum cloning on the qubits. We calculate the fidelity of this IDC procedure numerically and discuss its dependence on the mixedness of the input state. [Preview Abstract] |
Saturday, October 24, 2020 12:42PM - 12:54PM Live |
M05.00002: Investigating the speed limit of two-qubit entangling gates with superconducting qubits Joel Howard, Junling Long, Mustafa Bal, Ruichen Zhao, Tongyu Zhao, David Pappas, Zhexuan Gong, Meenakshi Singh Fast two-qubit entangling gates are essential for quantum computers with finite coherence times. Due to the limit of interaction strength among qubits, there exists a theoretical speed limit for a given two-qubit entangling gate. This speed limit has been explicitly found only for a two-qubit system and under the assumption of negligible single qubit gate time. We seek to demonstrate such a speed limit experimentally using two superconducting transmon qubits with a fixed capacitive coupling. Moreover, we investigate a modified speed limit when single qubit gate time is not negligible, as in any practical experimental setup. Finally, we discuss the generalization to multiple qubit systems where the coupling to additional qubits can significantly increase the speed limit of a two-qubit entangling gate, thus requiring the co-design of the quantum computer from both theorists and experimentalists for optimal gate performance. [Preview Abstract] |
Saturday, October 24, 2020 12:54PM - 1:06PM Live |
M05.00003: Quantum computational advantage with string order parameters of 1D symmetry-protected topological order Austin Daniel, Akimasa Miyake Nonlocal games with advantageous quantum strategies give arguably the most fundamental demonstration of the power of quantum resources over their classical counterparts. Recently, certain multiplayer generalizations of nonlocal games have been used to prove unconditional separations between small computational complexity classes of shallow-depth circuits. Here, we show advantageous strategies for these nonlocal games for generic ground states of one-dimensional symmetry-protected topological orders (SPTO), when a discrete invariant of SPTO known as a twist phase is nontrivial and -1. Our construction demonstrates that sufficiently large string order parameters of such SPTO are indicative of globally constrained correlations useful for the unconditional computational separation. [Preview Abstract] |
Saturday, October 24, 2020 1:06PM - 1:18PM Live |
M05.00004: Reliability of analog quantum simulation in chaotic systems Karthik Chinni, Pablo Poggi, Ivan Deutsch The era of Noise Intermediate Scale Quantum (NISQ) information processing is characterized by the absence of fully fault-tolerant quantum error correction, which raises a question about the reliability of such devices in the presence of imperfections.~ We seek to quantify the reliability of an analog quantum simulator in the presence of perturbations that render the dynamics chaotic in the classical limit. Quantum chaos is associated with hypersensitivity to perturbations, which may make a NISQ device unreliable.~ We do study this in the Lipkin-Meshkov-Glick (LMG) model, a simple many-body system that exhibits a quantum phase transition in its ground state and also a dynamical nonequilibrium quantum phase transition. We show that the critical point estimates of these phase transitions, obtained from the quantum simulation of its dynamics, are somewhat robust to the presence of this chaotic perturbation, even though other aspects of the system are fragile and therefore cannot be reliably extracted from this simulator. [Preview Abstract] |
Saturday, October 24, 2020 1:18PM - 1:30PM Live |
M05.00005: How tractable is the simulation of open quantum system dynamics of Ising models? Anupam Mitra, Tameem Albash, Akimasa Miyake, Ivan Deutsch A near-term goal for Noisy Intermediate Scale Quantum (NISQ) devices is quantum simulation of nonequilibrium dynamics in many-body systems [Preskill Quantum 2, 79 (2018)]. While the exact unitary dynamics of a closed many-body quantum systems is generally intractable, recent work has shown that approximate simulations of NISQ devices are tractable [Zhou, et al, arXiv:2002.07730; Noh, et al, arXiv:2003.13163]. We expect that classical simulation of certain quantum observables becomes tractable above a certain level of decoherence. We assume open quantum system dynamics given by a Lindblad master equation, which we solve using quantum trajectories and a matrix product state representation. We study this in the context of Ising spin chains in 1D, inspired by experiments using arrays of Rydberg atoms and trapped ions. We explore how decoherence allows for a larger truncation of the bond dimension of tensors in the matrix product state representation while still maintaining a good approximation to the exact dynamics. We find that for a fixed error budget, the complexity of the matrix product representation, is reduced for open quantum systems. This suggests that quantum simulation of many-body dynamics on NISQ devices may be classically tractable for some decoherence strengths. [Preview Abstract] |
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