Dissipative dynamics of quantum correlations in the strong-coupling regime

TL;DR

This paper investigates how non-RWA dissipative dynamics influence quantum correlations like entanglement and discord in a strongly coupled qubit-cavity system, revealing steady states independent of cavity decay and effects unique to non-RWA conditions.

Contribution

It introduces a Lindblad-type master equation that accurately describes strong-coupling dissipation, showing novel effects on quantum correlations not seen under RWA.

Findings

Steady states are cavity decay rate independent.

Non-RWA effects can induce steady state entanglement from initially unentangled states.

Non-RWA dynamics reverse initial state dependence of quantum correlations.

Abstract

The dynamics of entanglement and quantum discord between two identical qubits strongly interacting with a common single mode leaky cavity field have been investigated beyond the rotating wave approximation (RWA) by using recently derived Lindblad type quantum optical master equation [F. Beaudoin, J.M. Gambetta, A. Blais, Phys. Rev. A {\bf 84}, 043832 (2011)] that can describe the losses of the cavity field in a strong atom-field coupling regime. Contrary to previous investigations of the same model in the dissipative regime by using the standard Lindblad quantum optical master equation in a strong-coupling regime, the atom-field steady states are found to be cavity decay rate independent and have a very simple structure determined solely by the overlap of initial atomic state with the subradiant state which is valid for all coupling regimes. Non-RWA dynamics are found to have remarkable effects on the steady state quantum discord and entanglement that cannot be achieved under RWA conditions, for instance, they can induce steady state entanglement even for the initial states that have no overlap with the subradiant state. Moreover, the non-RWA dynamics are found to reverse the initial state dependence of steady state entanglement and quantum discord contrary to the RWA case.