Relaxation and Prethermalization in an Isolated Quantum System

Abstract

Understanding relaxation processes is an important unsolved problem in many areas of physics. A key challenge is the scarcity of experimental tools for the characterization of complex transient states. We used measurements of full quantum mechanical probability distributions of matter-wave interference to study the relaxation dynamics of a coherently split one-dimensional Bose gas and obtained comprehensive information about the dynamical states of the system. After an initial rapid evolution, the full distributions reveal the approach toward a thermal-like steady state characterized by an effective temperature that is independent from the initial equilibrium temperature of the system before the splitting process. We conjecture that this state can be described through a generalized Gibbs ensemble and associate it with prethermalization.

Experimental characterization of a quantum many-body system via higher-order correlations

“…1) [21]. Matter-wave interferometry [22][23][24] gives direct access to the spatially resolved relative phase ϕ(z) between the superfluids (see Methods).…”

“…To extract the spatially resolved relative phase between the superfluids we record the resulting matterwave interference pattern of the two 1D Bose gases after about 16 ms time-of-flight expansion using standard absorption imaging [23,30].…”

Rare‐region effects and dynamics near the many‐body localization transition

“…That such questions can be probed experimentally at all is the result of advances in preparing, controlling and measuring such systems in a variety of platforms, including ultracold atomic [14,15], trapped ion systems [16,17], superconducting qubit arrays [18], NV-centers [19] etc. These developments bring the investigation of outof-equilibrium many-body quantum dynamics within experimental reach; and, indeed, both the failure of thermalization in integrable one-dimensional quantum systems [6,20,21] and the presence of MBL regimes have been experimentally demonstrated [22][23][24][25][26][27].…”

Stationary behaviour of observables after a quantum quench in the spin-1/2 Heisenberg XXZ chain

“…Nonequilibrium dynamics in closed quantum systems, and in particular quantum quenches, have attracted much experimental [1][2][3][4][5][6] and theoretical attention in recent years. There is a growing consensus that integrable models exhibit important differences in behaviour as compared to non-integrable ones 41 .…”