Quantum Fisher Information from Randomized Measurements

Aniket Rath, Cyril Branciard, Anna Minguzzi, and Benoît Vermersch
Phys. Rev. Lett. 127, 260501 – Published 22 December 2021
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Abstract

The quantum Fisher information (QFI) is a fundamental quantity of interest in many areas from quantum metrology to quantum information theory. It can in particular be used as a witness to establish the degree of multiparticle entanglement in quantum many-body systems. In this work, we use polynomials of the density matrix to construct monotonically increasing lower bounds that converge to the QFI. Using randomized measurements we propose a protocol to accurately estimate these lower bounds in state-of-the-art quantum technological platforms. We estimate the number of measurements needed to achieve a given accuracy and confidence level in the bounds, and present two examples of applications of the method in quantum systems made of coupled qubits and collective spins.

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  • Received 7 June 2021
  • Accepted 17 November 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.260501

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & Technology

Authors & Affiliations

Aniket Rath1, Cyril Branciard2, Anna Minguzzi1, and Benoît Vermersch1,3,4

  • 1Université Grenoble Alpes, CNRS, LPMMC, 38000 Grenoble, France
  • 2Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
  • 3Center for Quantum Physics, University of Innsbruck, Innsbruck A-6020, Austria
  • 4Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, Innsbruck A-6020, Austria

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Issue

Vol. 127, Iss. 26 — 24 December 2021

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