# Recurrences in an isolated quantum many-body system

## TL;DR

This paper demonstrates recurrences of coherence and long-range order in a large, interacting quantum many-body system, revealing new insights into the dynamics of complex quantum systems after thermalization.

## Contribution

It shows that recurrences can be observed in large quantum systems by focusing on specific collective observables, despite the system's complexity.

## Key findings

- Recurrences of coherence observed in systems with thousands of particles
- Long-range order re-emerges after thermal-like states
- Experimental evidence of quantum recurrences in large systems

## Abstract

Even though the evolution of an isolated quantum system is unitary, the complexity of interacting many-body systems prevents the observation of recurrences of quantum states for all but the smallest systems. For large systems one can not access the full complexity of the quantum states and the requirements to observe a recurrence in experiments reduces to being close to the initial state with respect to the employed observable. Selecting an observable connected to the 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. This opens up a new window into the dynamics of large quantum systems even after they reached a transient thermal-like state.