Exact results on decoherence and entanglement in a system of N driven atoms and a dissipative cavity mode

TL;DR

This paper provides exact analytical solutions for the dynamics of decoherence and entanglement in a system of N driven atoms coupled to a dissipative cavity, revealing decoherence-free subspaces and methods to generate entangled states.

Contribution

It introduces exact results for decoherence, entanglement, and state generation in a many-atom cavity QED system, including decoherence-free subspaces and state monitoring techniques.

Findings

Identification of decoherence-free subspaces for the system and subsystems

Monitoring quantum coherence through atomic population measurements

Conditional generation of multi-partite entangled and cat-like states

Abstract

We solve the dynamics of an open quantum system where N strongly driven two-level atoms are equally coupled on resonance to a dissipative cavity mode. Analytical results are derived on decoherence, entanglement, purity, atomic correlations and cavity field mean photon number. We predict decoherence-free subspaces for the whole system and the N-qubit subsystem, the monitoring of quantum coherence and purity decay by atomic populations measurements, the conditional generation of atomic multi-partite entangled states and of cavity cat-like states. We show that the dynamics of atoms prepared in states invariant under permutation of any two components remains restricted within the subspace spanned by the completely symmetric Dicke states. We discuss examples and applications in the cases N=3,4.