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Experimental simulation of postselected closed timelike curves for decoding scrambled quantum information

Yi-Te Huang1,2,3, Hsiang-Wei Huang1,2, Jhen-Dong Lin1,2, Adam Miranowicz3,4, Neill Lambert3, Guang-Yin Chen5, Franco Nori3,6,*, and Yueh-Nan Chen1,2,7,†

  • *Contact author: fnori@riken.jp
  • †Contact author: yuehnan@mail.ncku.edu.tw
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Phys. Rev. Research 8, 023084 – Published 29 April, 2026

DOI: https://doi.org/10.1103/tm83-sxpm

Abstract

Quantum information scrambling (QIS) describes the rapid spread of initially localized information across an entire quantum many-body system through entanglement generation. Once scrambled, the original local information becomes encoded globally, inaccessible from any single subsystem. In this work, we introduce a circuit-based decoding protocol. By utilizing the concept of postselected closed timelike curves (PCTCs), we demonstrate how postselection allows us to interpret an ordinary quantum experiment as an example of a paradox-free trajectory, simulating a consistent time loop and reliable information recovery. Specifically, when conditioned on a final postselected outcome, this experiment can be interpreted as decoding the scrambled information even before the original information is generated. Furthermore, the success probability of the PCTC is governed by out-of-time-ordered correlations, which is a standard measure of QIS. We experimentally implement our protocol on cloud-based Quantinuum and IBM quantum processors. Our approach illuminates a unique quantum task under postselection: the causally consistent simulation of future-to-past scrambled information retrieval.

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Phys. Rev. Research 8, 023084– Published 29 April, 2026
  • Received 23 January 2025
  • Accepted 30 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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