Fluctuation-Induced Bistability of Fermionic Atoms Coupled to a Dissipative Cavity

TL;DR

This paper explores how fermionic atoms in an optical lattice coupled to a dissipative cavity exhibit fluctuation-induced bistability, revealing complex phase behavior beyond mean-field predictions.

Contribution

It demonstrates the emergence of bistability due to atom-cavity fluctuations, a phenomenon not captured by traditional mean-field theories.

Findings

Transition to self-organized phase at critical pump strength

Existence of bistability at higher pump strengths

Fluctuation-driven phenomena beyond mean-field approximation

Abstract

We investigate the steady state phase diagram of fermionic atoms subjected to an optical lattice and coupled to a high finesse optical cavity with photon losses. The coupling between the atoms and the cavity field is induced by a transverse pump beam. Taking fluctuations around the mean-field solutions into account, we find that a transition to a self-organized phase takes place at a critical value of the pump strength. In the self-organized phase the cavity field takes a finite expectation value and the atoms show a modulation in the density. Surprisingly, at even larger pump strengths two self-organized stable solutions of the cavity field and the atoms occur, signaling the presence of a bistability. We show that the bistable behavior is induced by the atoms-cavity fluctuations and is not captured by the mean-field approach.