Periodic cavity state revivals from atomic frequency combs

TL;DR

This paper provides a rigorous quantum theoretical analysis of atomic frequency combs in cavity QED, demonstrating near-perfect multi-photon state revival and high fidelity through energy shift compensation.

Contribution

It introduces a full quantum tensor-network approach to analyze atomic frequency combs in the strong coupling regime, revealing their ability to nearly perfectly absorb and re-emit multi-photon states.

Findings

Near-unity fidelity in state revival

Periodic re-emission of parity-flipped states

Effective compensation of energy shifts

Abstract

Spin ensembles with a comb-shaped spectrum have shown exciting properties as efficient quantum memories. Here, we present a rigorous theoretical study of such atomic frequency combs in the strong coupling limit of cavity QED, based on a full quantum treatment using tensor-network methods. Our results demonstrate that arbitrary multi-photon states in the cavity are almost perfectly absorbed by the spin ensemble and re-emitted as parity-flipped states at periodic time intervals. Fidelity values near unity are achieved in these revived states by compensating for energy shifts induced by the strong spin-cavity coupling through adjustments of individual coupling values of the teeth in the atomic frequency comb.