Frequency-up conversion and quantum swap gate in an optical cavity with atomic cloud

TL;DR

This paper proposes a scheme using a V-type atomic ensemble in an optical cavity to achieve frequency-up conversion and a high-fidelity quantum swap gate for intracavity fields, scalable with atom number.

Contribution

It introduces a novel method for mediating cavity field interactions via atomic ensembles, enabling scalable quantum operations with high fidelity.

Findings

Effective coupling scales as √N with atom number.

High-fidelity quantum swap gate achievable despite atomic spontaneous emission.

Frequency-up conversion demonstrated in the proposed scheme.

Abstract

A scheme is presented for realizing frequency-up conversion and a two-qubit quantum swap gate for intracavity fields. In the scheme, a V-type atomic ensemble prepared in their ground states collectively mediates the interaction between the two cavity modes. Under certain conditions, the cavity-field degree of freedom is decoupled from the atomic degrees of freedom, and the effective coupling strength between the two cavity modes scales up with $\sqrt{N}$ ($N$ is the number of atoms). The numerical simulation shows that the quantum swap gate still has a high fidelity under the influence of the atomic spontaneous emission and the decay of the cavity modes.