Quantifying and controlling prethermal nonergodicity in interacting Floquet matter

TL;DR

This study experimentally investigates prethermalization in a driven quantum system, mapping its properties across parameters, revealing controlled nonergodic regimes, and observing sequential thermalization processes.

Contribution

It provides the first comprehensive experimental map of prethermal Floquet matter, demonstrating control over its properties via drive parameters and interactions.

Findings

Quantified prethermal localization using inverse participation ratio.

Mapped drive-dependent properties over four decades of parameters.

Observed sequential formation of prethermal plateaux and ergodicity.

Abstract

The use of periodic driving for synthesizing many-body quantum states depends crucially on the existence of a prethermal regime, which exhibits drive-tunable properties while forestalling the effects of heating. This motivates the search for direct experimental probes of the underlying localized nonergodic nature of the wave function in this metastable regime. We report experiments on a many-body Floquet system consisting of atoms in an optical lattice subjected to ultrastrong sign-changing amplitude modulation. Using a double-quench protocol we measure an inverse participation ratio quantifying the degree of prethermal localization as a function of tunable drive parameters and interactions. We obtain a complete prethermal map of the drive-dependent properties of Floquet matter spanning four square decades of parameter space. Following the full time evolution, we observe sequential formation of two prethermal plateaux, interaction-driven ergodicity, and strongly frequency-dependent dynamics of long-time thermalization. The quantitative characterization of the prethermal Floquet matter realized in these experiments, along with the demonstration of control of its properties by variation of drive parameters and interactions, opens a new frontier for probing far-from-equilibrium quantum statistical mechanics and new possibilities for dynamical quantum engineering.