Extreme spin squeezing in the steady state of a generalized Dicke model

TL;DR

This paper proposes a cavity QED scheme to generate steady-state atomic spin squeezing using engineered atom-photon interactions, resulting in highly entangled states with potential for Heisenberg-limited measurements.

Contribution

It introduces a method to produce strongly spin-squeezed Dicke states in steady state via cavity-mediated Raman transitions with large dispersive coupling.

Findings

Steady-state spin squeezing achieved in a cavity QED system.

Generation of Dicke states with Heisenberg-limited metrological properties.

Presence of genuine multipartite entanglement among atoms.

Abstract

We present a scheme to generate steady-state atomic spin squeezing in a cavity QED system using cavity-mediated Raman transitions to engineer effective atom-photon interactions, which include both linear and nonlinear (dispersive) atom-cavity couplings, on a potentially equal footing. We focus on a regime where the dispersive coupling is very large and find that the steady state of the system can in fact be a strongly spin-squeezed Dicke state, $|N/2,0\rangle$, of the atomic ensemble. These states offer Heisenberg-limited metrological properties and feature genuine multipartite entanglement among the entire atomic ensemble.