Single-atom single-photon coupling facilitated by atomic-ensemble dark-state mechanisms

TL;DR

This paper introduces a novel method for coupling single atomic qubits to photons using atomic ensembles and dark-state mechanisms, enabling quantum gates with phase shifts.

Contribution

It presents a new approach utilizing atomic-ensemble dark states mediated by Rydberg interactions for efficient atom-photon coupling.

Findings

Enables quantum gates with zero and π phase shifts.

Uses Rydberg interactions to mediate coupling.

Achieves resonant coupling via collective dark states.

Abstract

We propose to couple single atomic qubits to photons incident on a cavity containing an atomic ensemble of a different species that mediates the coupling via Rydberg interactions. Subject to a classical field and the cavity field, the ensemble forms a collective dark state which is resonant with the input photon, while excitation of a qubit atom leads to a secondary "dark" state that splits the cavity resonance. The two different dark state mechanisms yield zero and $\pi$ reflection phase shifts and can be used to implement quantum gates between atomic and optical qubits.