Balancing Quantum Memories in Asymmetric Repeaters for High-Fidelity Entanglement Distribution

2026-04-27

AI Summary

This work addresses the mismatch in entanglement generation caused by asymmetric link distances in quantum repeaters. To mitigate decoherence losses arising from waiting times during entanglement swapping, the authors propose a dynamic optimal quantum memory allocation strategy that synchronizes entanglement generation at the left and right nodes. They derive, for the first time, a dynamic memory allocation scheme tailored to asymmetric repeater architectures and establish statistical lower bounds on end-to-end entanglement distribution rate and fidelity. By integrating quantum memory multiplexing, probabilistic entanglement modeling, and dynamic resource optimization, the proposed method achieves fidelity significantly higher than that of conventional repeaters while maintaining a comparable distribution rate, thereby demonstrating the effectiveness and superiority of dynamic allocation in asymmetric quantum networks.

Technology Category

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

Application Category

• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Security and Privacy: Large-scale security measurements

Abstract

At the core of the quantum Internet lie quantum repeaters that enable remote end-to-end entanglement generation. Fundamentally, the entanglement generation rate and fidelity of quantum repeaters constitute the bottleneck for end-to-end performance. To achieve high rates, quantum repeaters employ quantum memory multiplexing. In a high-rate standard repeater, each memory sequentially generates an entanglement with its neighboring nodes and then applies entanglement swapping. This, however, results in low fidelity due to decoherence of the first-formed entanglement in the sequential generation process. By allocating different numbers of memories to simultaneously form entanglements with the left and right adjacent nodes, quantum repeaters reduce high waiting times and achieve high fidelity. In such a repeater, a mismatch problem arises due to the difference between the probabilistic number of generated entanglements on both sides. Consequently, some entanglements remain stored until opposite entanglements are available. The mismatch problem reduces the repeater rate and particularly the entanglement fidelity. In this paper, we consider the mismatch problem in an asymmetric repeater with different distances to its adjacent nodes. To mitigate the mismatch problem, we derive a dynamic optimal memory allocation. Under the optimal allocation, we derive statistical lower bounds on the achievable rate and fidelity. We demonstrate that the optimal allocation significantly improves the fidelity while maintaining a comparable rate to the standard repeater. In contrast, our results show that fixed memory allocation may be detrimental to the fidelity.

Problem

• quantum repeaters
• entanglement distribution
• memory allocation
• fidelity
• asymmetric repeaters

Innovation

• quantum repeaters
• quantum memory allocation
• entanglement fidelity
• asymmetric repeater
• dynamic optimization