Out-of-Time-Ordered-Correlator Quasiprobabilities Robustly Witness Scrambling

José Raúl González Alonso, Nicole Yunger Halpern, and Justin Dressel
Phys. Rev. Lett. 122, 040404 – Published 1 February 2019
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Abstract

Out-of-time-ordered correlators (OTOCs) have received considerable recent attention as qualitative witnesses of information scrambling in many-body quantum systems. Theoretical discussions of OTOCs typically focus on closed systems, raising the question of their suitability as scrambling witnesses in realistic open systems. We demonstrate empirically that the nonclassical negativity of the quasiprobability distribution (QPD) behind the OTOC is a more sensitive witness for scrambling than the OTOC itself. Nonclassical features of the QPD evolve with timescales that are robust with respect to decoherence and are immune to false positives caused by decoherence. To reach this conclusion, we numerically simulate spin-chain dynamics and three measurement protocols (the interferometric, quantum-clock, and weak-measurement schemes) for measuring OTOCs. We target experiments based on quantum-computing hardware such as superconducting qubits and trapped ions.

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  • Received 23 June 2018

DOI:https://doi.org/10.1103/PhysRevLett.122.040404

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Interdisciplinary PhysicsGravitation, Cosmology & AstrophysicsCondensed Matter, Materials & Applied PhysicsQuantum Information, Science & Technology

Authors & Affiliations

José Raúl González Alonso1,*, Nicole Yunger Halpern2, and Justin Dressel1,3

  • 1Schmid College of Science and Technology, Chapman University, Orange, California 92866, USA
  • 2Institute for Quantum Information and Matter, Caltech, Pasadena, California 91125, USA
  • 3Institute for Quantum Studies, Chapman University, Orange, California 92866, USA

  • *Corresponding author. gonzalezalonso@chapman.edu

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Issue

Vol. 122, Iss. 4 — 1 February 2019

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