Strongly correlated excitation dynamics in an ultracold Rydberg gas

Abstract

The van-der-Waals interaction between ultracold atoms excited to highlying Rydberg states can lead to strongly correlated excitation dynamics [1, 2]. We study these correlations for resonant and off-resonant driving of cold atoms in a magneto-optical trap. In the resonant case we observe dynamical constraints similar to those found in glassy systems [3]. By contrast, for off-resonant driving facilitated excitations mediated by Rydberg-Rydberg interactions lead to avalanche-like events in which a chain reaction of successive excitations occurs. We show that this effect can be induced by a seed excitation and that the resulting full counting statistics of excitation events can be reproduced by a simple analytical model