Entanglement created by spontaneously generated coherence

TL;DR

This paper presents a scheme to generate steady-state entanglement between two cavity modes using driven multi-level atoms, exploiting spontaneously generated coherence and population imbalance in dressed states.

Contribution

It introduces a novel method for on-demand steady-state entanglement using atomic coherence and population control in a cavity QED setup.

Findings

Entanglement is maximized when atomic dressed states are imbalanced.

Degeneracy and coherence in a three-level atom enable entanglement tuning.

Entanglement depends on atomic dipole polarization and population trapping.

Abstract

We propose a scheme able to generate on demand a steady-state entanglement between two non-degenerate cavity modes. The scheme relies on the interaction of the cavity modes with driven two or three-level atoms which act as a coupler to build entanglement between the modes. We show that in the limit of a strong driving, crucial for the generation of entanglement between the modes is to imbalance populations of the dressed states of the driven atomic transition. In the case of a three-level V-type atom, we find that a stationary entanglement can be created on demand by tuning the Rabi frequency of the driving field to the difference between the atomic transition frequencies. The resulting degeneracy of the energy levels together with the spontaneously generated coherence generates a steady-state entanglement between the cavity modes. It is shown that the condition for the maximal entanglement coincides with the collapse of the atomic system into a pure trapping state. We also show that the creation of entanglement depends strongly on the mutual polarization of the transition atomic dipole moments.