Single-site measurements as probes of many-body quantum chaos.

Vallejo-Fabila, Isaías; Das, Adway Kumar; Choudhury, Sayan; Santos, Lea F · Phys Rev E · 2025

basic_science · Level V

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Abstract

We demonstrate that the dynamics of an observable localized at a single-site is sufficient to determine whether a many-body quantum system exhibits level statistics characteristic of random matrix theory, which is a widely used diagnostic of quantum chaos. Specifically, we analyze the spin autocorrelation function at a single site evolving under a disordered spin-1/2 chain, a setup realizable in ongoing experimental platforms. We also investigate the partial (subsystem) survival probability, recently measured in cold-atom experiments, thereby broadening discussions on detecting many-body quantum chaos via survival probability [Phys. Rev. Res. 7, 013181 (2025)2643-156410.1103/PhysRevResearch.7.013181]. Given the precision and timescales currently achievable, our results indicate that the detection of many-body quantum chaos through dynamical observables is feasible but constrained to small system sizes.