Entanglement dynamics and decoherence of an atom coupled to a dissipative cavity field

TL;DR

This paper studies how entanglement and decoherence evolve in a driven atom-cavity system with dissipation, revealing conditions for quantum teleportation and Bell inequality violations.

Contribution

It provides a detailed analysis of entanglement dynamics, Bell inequality violations, and quantum teleportation capabilities in a dissipative atom-cavity system, highlighting new insights into quantum information processing.

Findings

Cavity decay affects entanglement and Bell violation.

Entangled states can teleport qubits with fidelity surpassing classical limits.

Bell-CHSH inequality may not always be violated despite entanglement.

Abstract

In this paper, we investigate the entanglement dynamics and decoherence in the interacting system of a strongly driven two-level atom and a single mode vacuum field in the presence of dissipation for the cavity field. Starting with an initial product state with the atom in a general pure state and the field in a vacuum state, we show that the final density matrix is supported on ${\mathbb C}^2\otimes{\mathbb C}^2$ space, and therefore, the concurrence can be used as a measure of entanglement between the atom and the field. The influences of the cavity decay on the quantum entanglement of the system are also discussed. We also examine the Bell-CHSH violation between the atom and the field and show that there are entangled states for which the Bell-BCSH inequality is not violated. Using the above system as a quantum channel, we also investigate the quantum teleportation of a generic qubit state and also a two-qubit entangled state, and show that in both cases the atom-field entangled state can be useful to teleport an unknown state with fidelity better than any classical channel.