Absorption-based Quantum Communication with NV centres

TL;DR

This paper proposes an absorption-based quantum communication scheme using NV centers, employing heralded photon absorption and cavity enhancement to achieve near-unity success probability for entanglement swapping in quantum networks.

Contribution

It introduces a novel method for entanglement swapping with NV centers using heralded absorption and cavity techniques to improve efficiency.

Findings

Heralded photon absorption can be used for entanglement swapping with NV centers.

Cavity enhancement significantly increases absorption efficiency.

The scheme approaches near-unity success probability under low-loss conditions.

Abstract

We propose a scheme for performing an entanglement-swapping operation within a quantum communications hub (a Bell like measurement) using an NV centre's $|\pm 1\rangle \leftrightarrow | A_2 \rangle$ optical transition. This is based on the heralded absorption of a photon resonant with that transition. The quantum efficiency of a single photon absorption is low but can be improved by placing the NV center inside a micro cavity to boost the interaction time and further by recycling the leaked photon back into the cavity after flipping its phase and/or polarisation. Throughout this process, the NV is repeatedly monitored via a QND measurement that heralds whether or not the photon absorption has succeeded. Upon success we know a destructive Bell measurement has occurred between that photon and NV center. Given low losses and a high per-pass absorption probability, this scheme allows the total success probability to approach unity. With long electron spin coherence times possible at low temperatures, this component could be useful within a memory-based quantum repeater or relay.