Entanglement between two qubits one of which interacts with a thermal field

TL;DR

This study explores how a thermal field can induce entanglement between two dipole-coupled atoms, one inside a cavity and one outside, highlighting the effects of initial atomic coherence and thermal photon number.

Contribution

It introduces a model where only one atom interacts with a thermal field, analyzing entanglement dynamics with respect to atomic coherence and thermal photon number.

Findings

Thermal fields can generate high entanglement at low photon numbers.

Atoms can become entangled even if both start in excited states.

Entanglement is weakly affected by dipole-dipole interaction strength for coherent states.

Abstract

In this paper, we have investigated the entanglement between two dipole coupled two-level atoms. The model, in which only one atom is trapped in an lossless cavity and interacts with single-mode thermal field, and the other one can be spatially moved freely outside the cavity has been carried out. We have considered the effect of the atomic coherence on the entanglement behavior. We have shown that a thermal field might cause high entanglement between the atoms both for coherent and incoherent initial atomic states only for small values of the cavity mean photon number. In the considered model the atoms would get entangled even when both atoms are initially in the excited state. We have also derived that the degree of entanglement is weakly dependent on the strength of dipole-dipole interaction for coherent initial states.