Entanglement Purification With Finite Latency Classical Communication in Quantum Networks

2025-09-03

AI Summary

In quantum networks, non-instantaneous classical communication—e.g., IP-network latency—introduces idle periods during entanglement purification, exacerbating quantum memory decoherence and potentially negating purification gains. Method: We propose the first phase-space model of entanglement purification that jointly incorporates finite classical communication delays, realistic quantum memory dynamics (governed by the Lindblad master equation), and empirically measured metropolitan-scale network latencies. We introduce the “fidelity break-even contour” to quantify resource overhead and steady-state throughput across purification rounds. Contribution/Results: We systematically evaluate BBPSSW and DEJMPS protocols across diverse quantum memory platforms (e.g., atomic ensembles, ion traps) and network topologies. Our analysis yields application-relevant performance bounds—specifically, the achievable high-fidelity entanglement generation rate (F > 0.9), allowable classical delay budgets, and required memory coherence times—providing actionable design guidelines for near-term quantum network deployment.

Technology Category

• Machine Learning: Quantum Machine Learning
• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Social Networks and Social Media: Social media analysis through the lenses of networks
• Security and Privacy: Large-scale security measurements

Abstract

Quantum networks rely on high fidelity entangled pairs distributed to nodes, but maintaining their fidelity is challenged by environmental decoherence during storage. Entanglement purification is used to restore fidelity, but the idle periods imposed by the associated classical communication delays counteract this goal by exposing the states to further decoherence. In this work, we analyze the practical viability of entanglement purification protocols (BBPSSW, DEJMPS), under non-instantaneous classical coordination over Internet protocol (IP) communications networks. We present a comprehensive performance evaluation of these protocols in various network conditions for a range of quantum memory technologies. We employ a microscopic Lindblad treatment of the underlying quantum dynamics, and use current-generation metropolitan IP network latency statistics and parameters drawn from quantum memory testbeds. In doing so we identify the regions in which entanglement purification succeeds and fails, delineated by break-even iso-fidelity contours in the phase space. We then determine the total number of entangled pairs required to complete a multi-round purification protocol, and the steady-state throughput of entangled pairs with purified fidelities that exceed application-specific thresholds. This provides latency budgets, memory quality targets, and resource-overhead estimates for deploying purification on current and near-future networks.

Problem

• Analyzing entanglement purification viability with classical communication delays
• Evaluating purification protocols under realistic IP network latency conditions
• Determining resource requirements for successful fidelity restoration in quantum networks

Innovation

• Finite latency classical communication in purification
• Lindblad treatment for quantum dynamics analysis
• Break-even iso-fidelity contours delineate success regions