PT  - JOURNAL ARTICLE
AU  - Rauer, Bernhard
AU  - Erne, Sebastian
AU  - Schweigler, Thomas
AU  - Cataldini, Federica
AU  - Tajik, Mohammadamin
AU  - Schmiedmayer, Jörg
TI  - Recurrences in an isolated quantum many-body system
AID  - 10.1126/science.aan7938
DP  - 2018 Apr 20
TA  - Science
PG  - 307--310
VI  - 360
IP  - 6386
4099  - http://science.sciencemag.org/content/360/6386/307.short
4100  - http://science.sciencemag.org/content/360/6386/307.full
SO  - Science2018 Apr 20; 360
AB  - A finite isolated system should return almost to its initial state if it evolves for long enough. For a large system, “long enough” is often unfeasibly long. Rauer et al. found just the right conditions to observe the recurrence of the initial state in a system of two one-dimensional superfluids with thousands of atoms in each. The superfluids were initially coupled—locking their quantum mechanical phases together—and then allowed to evolve independently. After the uncoupling, the researchers observed their phases regaining coherence two more times.Science, this issue p. 307The complexity of interacting quantum many-body systems leads to exceedingly long recurrence times of the initial quantum state for all but the smallest systems. For large systems, one cannot probe the full quantum state in all its details. Thus, experimentally, recurrences can only be determined on the level of the accessible observables. Realizing a commensurate spectrum of collective excitations in one-dimensional superfluids, we demonstrate recurrences of coherence and long-range order in an interacting quantum many-body system containing thousands of particles. Our findings will enable the study of the coherent dynamics of large quantum systems even after they have reached a transient thermal-like state.