High-Probability Heralded Entanglement via Repeated Spin-Photon Phase Encoding with Moderate Cooperativity

TL;DR

This paper introduces a repeated spin-photon phase encoding scheme that significantly increases the success probability of generating high-fidelity remote entanglement in moderate-cooperativity systems, advancing quantum networking.

Contribution

It proposes a novel repeated interaction protocol that enhances entanglement success rates in spin-cavity systems with moderate cooperativity, overcoming limitations of single-shot methods.

Findings

Achieves high-fidelity entanglement at cooperativity C~1.

Enables higher encoding efficiency with spectral-width-scaling photons.

Provides a practical route for hybrid quantum networks with losses.

Abstract

We propose a heralded high-probability scheme to generate remote entanglement between moderate-cooperativity spin-cavity registers with high fidelity. In conventional single-shot interfaces, limited cooperativity restricts the spin-conditional optical response and thus strongly suppresses the success probability. Our proposal instead recycles a single incident photon for repeated interactions with the spin-cavity register, such that a small spin-conditional phase shift acquired on each round trip accumulates coherently to enable remote entanglement. Moreover, the repeated scheme enables higher spin-photon encoding efficiency by using a spectral-width-scaling photon pulse with a shorter duration. We show that, for realistic imperfections and losses, this repeated phase-encoding approach produces high-fidelity entangled states with an appreciable success probability even at cooperativity $C\sim1$. Our protocol is particularly well suited to weakly coupled, cavity-based solid-state spin platforms and provides a route toward hybrid, photon-loss-tolerant distributed quantum computing.