Quantifying and Controlling Prethermal Nonergodicity in Interacting Floquet Matter
Singh, K, Fujiwara, CJ, Geiger, ZA, Simmons, EQ, Lipatov, M, Cao, A, Dotti, P, Rajagopal, SV, Senaratne, R, Shimasaki, T, Heyl, M, Eckardt, A, Weld, DM
Abstract
The use of periodic driving for synthesizing many-body quantum states depends\ncrucially on the existence of a prethermal regime, which exhibits drive-tunable\nproperties while forestalling the effects of heating. This motivates the search\nfor direct experimental probes of the underlying localized nonergodic nature of\nthe wave function in this metastable regime. We report experiments on a\nmany-body Floquet system consisting of atoms in an optical lattice subjected to\nultrastrong sign-changing amplitude modulation. Using a double-quench protocol\nwe measure an inverse participation ratio quantifying the degree of prethermal\nlocalization as a function of tunable drive parameters and interactions. We\nobtain a complete prethermal map of the drive-dependent properties of Floquet\nmatter spanning four square decades of parameter space. Following the full time\nevolution, we observe sequential formation of two prethermal plateaux,\ninteraction-driven ergodicity, and strongly frequency-dependent dynamics of\nlong-time thermalization. The quantitative characterization of the prethermal\nFloquet matter realized in these experiments, along with the demonstration of\ncontrol of its properties by variation of drive parameters and interactions,\nopens a new frontier for probing far-from-equilibrium quantum statistical\nmechanics and new possibilities for dynamical quantum engineering.