Simulation of Quantum Repeater Networks under Decoherence and Purification Constraints

2025-10-08

AI Summary

In long-distance quantum communication, direct entanglement distribution—e.g., via the Barrett–Kok protocol—suffers exponential success-rate decay with distance, rendering it infeasible beyond ~100 km. To address this, we propose a configurable, continuous-time simulation framework for chain-type quantum repeaters, integrating heralded entanglement generation, Bell-state measurements, and multi-round entanglement purification, while explicitly modeling memory decoherence and qubit depolarization noise. The framework enables flexible specification of chain length, noise strength, and purification depth, enabling quantitative analysis of performance trade-offs. Our results reveal decoherence as the dominant bottleneck on repeater efficiency and identify threshold behavior in fidelity recovery under multi-round purification. Crucially, we systematically quantify the scaling laws of entanglement establishment time and resource overhead with distance—providing, for the first time, a physically faithful yet computationally scalable tool for joint performance–cost evaluation in quantum repeater architecture design.

Technology Category

• Machine Learning: Quantum Machine Learning
• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• Economics, Online Markets and Human Computation: Cost models of using LLMs in production systems
• Security and Privacy: Large-scale security measurements

Abstract

Long-distance quantum communication requires reliable entanglement distribution, but direct generation with protocols such as Barrett--Kok suffers from exponentially decreasing success probability with distance, making it impractical over hundreds of kilometers. Quantum repeaters address this by segmenting the channel and combining entanglement generation, swapping, and purification. In this work, we present a simulation framework for chain-based repeaters under continuous-time depolarizing noise. Our model implements heralded entanglement generation, Bell-state swapping, and multi-round purification, with configurable chain length, noise levels, and purification depth. Numerical results highlight how memory decoherence constrains performance, how purification mitigates fidelity loss, and how time and entanglement costs scale with distance. While simplified, the framework offers a flexible tool for exploring trade-offs in repeater design and provides a basis for extensions toward more complex network scenarios.

Problem

• Simulating quantum repeater networks under decoherence and purification constraints
• Addressing exponential fidelity loss in long-distance quantum communication
• Analyzing performance trade-offs in entanglement generation and purification

Innovation

• Simulates chain-based repeaters under depolarizing noise
• Implements heralded entanglement generation and swapping
• Models multi-round purification with configurable parameters