Resilience of scrambling measurements

TL;DR

This paper introduces a renormalization protocol that accurately measures quantum scrambling through out-of-time-ordered correlators, even with experimental imperfections and decoherence, simplifying the study of quantum chaos.

Contribution

The authors present a novel renormalization scheme that enables reliable scrambling measurements without perfect time-reversal control, applicable to realistic noisy quantum systems.

Findings

Protocol effectively extracts ideal correlators up to the scrambling time.

Demonstrated robustness against experimental imperfections and decoherence.

Applicable to a variety of quantum models with sizable errors.

Abstract

Most experimental protocols for measuring scrambling require time evolution with a Hamiltonian and with the Hamiltonian's negative counterpart (backwards time evolution). Engineering controllable quantum many-body systems for which such forward and backward evolution is possible is a significant experimental challenge. Furthermore, if the system of interest is quantum-chaotic, one might worry that any small errors in the time reversal will be rapidly amplified, obscuring the physics of scrambling. This paper undermines this expectation: We exhibit a renormalization protocol that extracts nearly ideal out-of-time-ordered-correlator measurements from imperfect experimental measurements. We analytically and numerically demonstrate the protocol's effectiveness, up to the scrambling time, in a variety of models and for sizable imperfections. The scheme extends to errors from decoherence by an environment.