Cavity-induced chiral states of fermionic quantum gases

TL;DR

This paper studies how cavity-induced interactions in ultra-cold fermionic gases confined to ladder structures lead to the spontaneous formation of chiral states with artificial magnetic fields, revealing rich phase diagrams and transition behaviors.

Contribution

It demonstrates the emergence of chiral insulating and liquid states in fermionic gases due to cavity feedback mechanisms, a novel insight into cavity-QED systems with fermions.

Findings

Spontaneous emergence of finite cavity field amplitude.

Formation of chiral insulating and liquid states with chiral currents.

Transition to chiral states can be sudden or gradual depending on parameters.

Abstract

We investigate ultra-cold fermions placed into an optical cavity and subjected to optical lattices which confine the atoms to ladder structures. A transverse running-wave laser beam induces together with the dynamical cavity field a two-photon Raman-assisted tunneling process with spatially dependent phase imprint along the rungs of the ladders. We identify the steady states which can occur by the feedback mechanism between the cavity field and the atoms. We find the spontaneous emergence of a finite cavity field amplitude which leads to an artificial magnetic field felt by the fermionic atoms. These form a chiral insulating or chiral liquid state carrying a chiral current. We explore the rich state diagram as a function of the power of the transverse laser beam, the atomic filling, and the phase imprint during the cavity-induced tunneling. Both a sudden onset or a slow exponential activation with the transverse laser power of the self-organized chiral states can occur.