Phases of driven two-level systems with nonlocal dissipation

Abstract

We study an array of two-level systems arranged on a lattice and illuminated by an external plane wave which drives a dipolar transition between the two energy levels. In this set up, the two-level systems are coupled by dipolar interactions and subject to nonlocal dissipation, so behave as an open many-body quantum system. We investigate the long-time dynamics of the system at the mean-field level, and use this to determine a phase diagram as a function of external drive and detuning. We find a multitude of phases including antiferromagnetism, spin density waves, oscillations and phase bistabilities. We investigate these phases in more detail and explain how nonlocal dissipation plays a role in the long-time dynamics. Furthermore, we discuss what features would survive in the full quantum description.

Bistable optical transmission through arrays of atoms in free space

“…However, bistability can also be found less commonly in systems where it is intrinsic, generated only by interactions within the sample, and has so far been observed in Yb 3+ ions in solid-state crystals at cryogenic temperatures [20] and in highly-excited Rydberg atoms in the microwave regime [21]. Intrinsic bistability was thought to be unachievable for atoms in the optical regime, but recent theoretical studies of many-body systems suggest that interaction-mediated bistability is more generic and possible in a variety of systems with short-and long-range interactions [22][23][24]. In particular, we recently demonstrated [25] that intrinsic bistability and optically-induced phases emerge in arrays of atoms at sufficiently high densities, due to resonant light-mediated dipole-dipole (DD) interactions and that these could be identified in coherently and incoherently scattered light.…”

Quantum and nonlinear effects in light transmitted through planar atomic arrays

“…Finding situations in which the predictions of SCEs observably differ from the full QME solution therefore identifies light-induced quantum effects in the transmitted light. Conversely, regimes where quantum fluctuations are minimal allow for the simulation of much larger systems than are accessible with QME , and also test the validity of related approaches in other contexts, based, e.g., on mean-field approximations, intensity expansions, or truncations of the correlations [58][59][60][61][62] .…”

Signatures of optical phase transitions in superradiant and subradiant atomic arrays

“…It is generally known from past bistability studies [43][44][45]48,52,64 that mean-field bistabilities coincide with enhanced quantum fluctuations, which can be understood as tunnelling between the two mean-field solutions. The corresponding quantum distribution is then bimodal.…”

“…Intrinsic bistability is a process where phase transitions are generated by the self-interactions of the sample, and despite having been observed in highly-excited Rydberg atoms in the microwave regime 49 , intrinsic bistability was for a long time considered unachievable for atoms with light-mediated interactions. Recent theoretical studies that also take into account the spatial structure of the many-body systems suggest that intrinsic bistability and phase transitions are more generic and could occur in a variety of systems with short-and long-range interactions [50][51][52] .…”