Monitoring atom-atom entanglement and decoherence in a solvable tripartite open system in cavity QED

TL;DR

This paper provides an analytical solution for the dynamics of two strongly-driven atoms in a dissipative cavity, revealing entanglement behavior, decoherence-free subspaces, and the generation of Schrödinger-cat-like states.

Contribution

It introduces a fully analytical model of atom-atom entanglement and decoherence in cavity QED, identifying decoherence-free subspaces and state generation mechanisms.

Findings

Initial atom-atom entanglement cannot be increased.

Existence of a decoherence-free subspace preserving entanglement.

Generation of Schrödinger-cat-like states and entanglement conditioned by measurements.

Abstract

We present a fully analytical solution of the dynamics of two strongly-driven atoms resonantly coupled to a dissipative cavity field mode. We show that an initial atom-atom entanglement cannot be increased. In fact, the atomic Hilbert space divides into two subspaces, one of which is decoherence free so that the initial atomic entanglement remains available for applications, even in presence of a low enough atomic decay rate. In the other subspace a measure of entanglement, decoherence, and also purity, are described by a similar functional behavior that can be monitored by joint atomic measurements. Furthermore, we show the possible generation of Schr\"odinger-cat-like states for the whole system in the transient regime, as well as of entanglement for the cavity field and the atom-atom subsystems conditioned by measurements on the complementary subsystem.