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Dynamic Routing in Space-Ground Integrated Quantum Networks

Tianjie Hu, Jindi Wu, Qun Li

TL;DR

This work addresses routing entanglement in space-ground integrated quantum networks that combine satellites and ground switches under finite capacities and probabilistic entanglement. It formulates the routing problem as a centralized integer program and solves it with two approaches: a Linear Relaxation method and a Greedy algorithm, enabling timely scheduling of entanglement purification and swapping. A key contribution is translating edge fidelities into additive noise via $\mu_e = \log(1/\gamma_e)$ and purification effects $p_e = \mu_e/\kappa_e$, enabling linear constraints and a tunable noise threshold $N^{th}$ to balance throughput and fidelity. Evaluations show that Linear Relaxation generally achieves higher throughput with controllable fidelity, while Greedy offers fast scheduling with more variable performance, illustrating a practical trade-off for global quantum networks.

Abstract

Quantum networks emerge as fundamental frameworks for addressing various large-scale problems. There are two primary architectures: space-based quantum networks, which deploy satellites with free space channels to interconnect users, and ground-based quantum networks, which utilize optical fibers to interconnect users. In this paper, we explore space-ground integrated quantum networks that incorporate both satellites and optical fibers into the infrastructure. This integrated network features three forms of communication: using only free space links, only ground links, or a hybrid usage of free space and ground links. We formulate the routing problem in space-ground integrated quantum networks as an integer programming and propose two solutions: using a linear relaxation and a greedy algorithm. The linear relaxation algorithm allows timely scheduling of additional entanglement purification, whereas the greedy algorithm enables quick scheduling. Simulation results demonstrate their effective balancing between network throughput and communication fidelity.

Dynamic Routing in Space-Ground Integrated Quantum Networks

TL;DR

This work addresses routing entanglement in space-ground integrated quantum networks that combine satellites and ground switches under finite capacities and probabilistic entanglement. It formulates the routing problem as a centralized integer program and solves it with two approaches: a Linear Relaxation method and a Greedy algorithm, enabling timely scheduling of entanglement purification and swapping. A key contribution is translating edge fidelities into additive noise via and purification effects , enabling linear constraints and a tunable noise threshold to balance throughput and fidelity. Evaluations show that Linear Relaxation generally achieves higher throughput with controllable fidelity, while Greedy offers fast scheduling with more variable performance, illustrating a practical trade-off for global quantum networks.

Abstract

Quantum networks emerge as fundamental frameworks for addressing various large-scale problems. There are two primary architectures: space-based quantum networks, which deploy satellites with free space channels to interconnect users, and ground-based quantum networks, which utilize optical fibers to interconnect users. In this paper, we explore space-ground integrated quantum networks that incorporate both satellites and optical fibers into the infrastructure. This integrated network features three forms of communication: using only free space links, only ground links, or a hybrid usage of free space and ground links. We formulate the routing problem in space-ground integrated quantum networks as an integer programming and propose two solutions: using a linear relaxation and a greedy algorithm. The linear relaxation algorithm allows timely scheduling of additional entanglement purification, whereas the greedy algorithm enables quick scheduling. Simulation results demonstrate their effective balancing between network throughput and communication fidelity.
Paper Structure (14 sections, 5 equations, 3 figures, 1 table, 1 algorithm)

This paper contains 14 sections, 5 equations, 3 figures, 1 table, 1 algorithm.

Table of Contents

  1. Introduction
  2. Related Work
  3. Preliminaries
  4. Free space and ground connections
  5. Satellite constellations
  6. Noise and Loss model
  7. Problem Formulation
  8. Routing Procedure
  9. Mathematical Formulation
  10. Proposed Solutions
  11. Linear Relaxation Algorithm
  12. Greedy Algorithm
  13. Evaluation
  14. Conclusion

Figures (3)

  • Figure 1: Space-ground integrated quantum network. Users communicate with each other through satellite-based free space links and fiber-based ground links.
  • Figure 2: (a) Connections between two users in a space-ground integrated quantum network. (b) End-to-end communication between the two users, where routing paths can be conducted through (1) free space links, (2) a hybrid usage of free space and ground links, or (3) ground links. Actual choices are made by the routing protocol in the network.
  • Figure 3: (a.1) Comparison between Linear and Greedy in different network scenarios over three metrics: fidelity, throughput, and latency. (a.2) Detailed comparison on network throughput. (b) Performance of Linear with respect to its configurable parameter Noise threshold.