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

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_gate approx 99.93\%; (ii) atom-photon conversion via Raman transitions, achieving directional emission $η_dir approx 35\%$ and single-node efficiency η_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.