Recurrences in an isolated quantum many-body system

Abstract

Recurring coherence 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. 307