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Analytically Continuing the Randomized Measurement Toolbox

Akash Vijay1, Ayush Raj2,*, Jonah Kudler-Flam3, Benoît Vermersch4,5, Andreas Elben6,7, and Laimei Nie2

  • *Contact author: raj42@purdue.edu
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Phys. Rev. Lett. 137, 100202 – Published 2 September, 2026

DOI: https://doi.org/10.1103/837t-68bf

Abstract

We develop a framework for extracting nonpolynomial analytic functions of density matrices in randomized measurement experiments by a method of analytical continuation. A central advantage of this approach, dubbed stabilized analytic continuation (SAC), is its robustness to statistical noise arising from finite repetitions of a quantum experiment, making it well suited to realistic quantum hardware. As a demonstration, we use SAC to estimate the von Neumann entanglement entropy of a numerically simulated quenched Néel state from Rényi entropies estimated via the randomized measurement protocol. We then apply the method to experimental Rényi data from a trapped-ion quantum simulator experiment, extracting subsystem von Neumann entropies at different evolution times. Finally, we briefly note that the SAC framework is readily generalizable to obtain other nonlinear diagnostics, such as the logarithmic negativity and Rényi relative entropies.

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Outline

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Phys. Rev. Lett. 137, 100202– Published 2 September, 2026
  • Received 29 January 2026
  • Revised 28 May 2026
  • Accepted 6 July 2026
Article part of CHORUS
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