Cavity-Free Distributed Quantum Computing with Rydberg Ensembles via Collective Enhancement

TL;DR

This paper proposes a cavity-free quantum networking architecture using Rydberg ensembles, achieving high-fidelity entanglement and efficient remote quantum communication without optical cavities.

Contribution

It introduces a novel cavity-free protocol leveraging Rydberg blockade and collective emission for scalable distributed quantum computing.

Findings

Local entanglement fidelity ~99.93%

Remote Bell state fidelity >97.5%

Entanglement rate >600 Hz at 20 km

Abstract

A complete architecture for cavity-free quantum networking based on collective enhancement in Rydberg atom ensembles is presented. The protocol exploits Rydberg blockade and phase-matched directional emission to eliminate optical cavities without sacrificing performance. The architecture comprises three steps: (i) local control-ensemble entanglement via Rydberg blockade with fidelity $F_{\mathrm{gate}} \approx 99.93\%$; (ii) atom-photon conversion via Raman transitions, achieving directional emission ($\eta_{\mathrm{dir}} \approx 35\%$) and single-node efficiency $\eta_{\mathrm{node}} \approx 19\%$; and (iii) remote atom-atom entanglement via Hong-Ou-Mandel interference, producing Bell states with fidelity $F > 97.5\%$. With quantum memories enabling retry protocols, entanglement generation rates exceed $600$ Hz at 20 km separation. This cavity-free approach provides a practical and scalable pathway for distributed quantum computing and secure quantum communication.