Bistability vs. Metastability in Driven Dissipative Rydberg Gases

TL;DR

This study explores whether a bistable phase exists in driven dissipative Rydberg gases, finding evidence for metastability and cluster formation but no true global bistability due to finite correlation lengths.

Contribution

The paper provides experimental and theoretical evidence that Rydberg gases exhibit metastable states and clustering without true bistability, challenging previous assumptions.

Findings

Finite correlation times suggest absence of global bistability.

Formation of finite-sized Rydberg clusters observed.

Metastable states linked to bimodal distributions and hysteresis.

Abstract

We investigate the possibility of a bistable phase in an open many-body system. To this end we discuss the microscopic dynamics of a continuously off-resonantly driven Rydberg lattice gas in the regime of strong decoherence. Our experimental results reveal a prolongation of the temporal correlations with respect to the lifetime of a single Rydberg excitation and show strong evidence for the formation of finite-sized Rydberg excitation clusters in the steady state. We simulate our data using a simplified and a full many-body rate-equation model. The results are compatible with the formation of metastable states associated with a bimodal counting distribution as well as dynamic hysteresis. A scaling analysis reveals however, that the correlation times remain finite for all relevant system parameters. This suggest that the Rydberg aggregate is composed of many small clusters and all correlation lengths remain finite. This is a strong indication for the absence of a global bistable phase, previously suggested to exist in this system.