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arXiv:2603.25563

Stochastic Multipath Routing for High-Throughput Entanglement Distribution in Quantum Repeater Networks

Ankit Mishra, Kang Hao Cheong

quant-phphysics.soc-phSubmitted Mar 26, 2026• Announced Mar 27, 2026• 0 citations• Revised Mar 28, 2026 (v2)
v1 · Mar 26, 2026v2 · Mar 28, 2026
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Abstract

Quantum repeater networks distribute entanglement over lossy links while many users share a limited pool of entangled pairs. Most existing routing schemes either always use a single best path or rely on global optimizations that are hard to run in real time. Here we propose and analyze a simple alternative: a stochastic multipath rule in which each entanglement request is sent at random along one of several edge-disjoint repeater paths, with a single parameter that controls the bias between shorter and longer routes. Using a distance-dependent lossy network model with finite per-link capacities and probabilistic entanglement swapping, we develop an analytic description of the resulting end-to-end entanglement rate as a function of this bias and validate it with large-scale numerical simulations. We find that an intermediate bias consistently outperforms both deterministic extremes across distances, traffic patterns, attenuation, swapping noise, and congestion, bringing the rate close to simple capacity upper bounds and making link usage more even across networks. These results identify stochastic multipath routing as a lightweight classical control strategy for boosting performance and scalability in near-term quantum repeater networks.

Comments
11 pages, 6 figures in main text, 3 figures in SM

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Quantum repeater networks distribute entanglement over lossy links while many users share a limited pool of entangled pairs. Most existing routing schemes either always use a single best path or rely on global optimizations that are hard to run in real time. Here we propose and analyze a simple alternative: a stochastic multipath rule in which each entanglement request is sent at random along one of several edge-disjoint repeater paths, with a single parameter that controls the bias between shorter and longer routes. Using a distance-dependent lossy network model with finite per-link capacities and probabilistic entanglement swapping, we develop an analytic description of the resulting end-to-end entanglement rate as a function of this bias and validate it with large-scale numerical simulations. We find that an intermediate bias consistently outperforms both deterministic extremes across distances, traffic patterns, attenuation, swapping noise, and congestion, bringing the rate close to simple capacity upper bounds and making link usage more even across networks. These results identify stochastic multipath routing as a lightweight classical control strategy for boosting performance and scalability in near-term quantum repeater networks.
With the emergence of the Quantum Internet, the need for advanced quantum networking techniques has significantly risen. Various models of quantum repeaters have been presented, each delineating a unique strategy to ensure quantum communication over long distances. We focus on repeaters that employ entanglement generation and swapping. This revolves around establishing remote end-to-end entanglement through repeaters, a concept we denote as the “quantum-native” repeaters (also called “first-generation” repeaters in some literature). The challenges in routing with quantum-native repeaters arise from probabilistic entanglement generation and restricted coherence time. Current approaches use synchronized time slots to search for entanglement-swapping paths, resulting in inefficiencies. Here, we propose a new set of asynchronous routing protocols for quantum networks by incorporating the idea of maintaining a dynamic topology in a distributed manner, which has been extensively studied in classical routing for lossy networks, such as using a destination-oriented directed acyclic graph or a spanning tree. The protocols update the entanglement-link topology asynchronously, identify optimal entanglement-swapping paths, and preserve unused direct-link entanglements. Our results indicate that asynchronous protocols achieve a larger upper bound with an appropriate setting and significantly higher entanglement rate than existing synchronous approaches, and the rate increases with coherence time, suggesting that it will have a much more profound impact on quantum networks as technology advances.
Abstract Remote quantum entanglement can enable numerous applications including distributed quantum computation, secure communication, and precision sensing. We consider how a quantum network—nodes equipped with limited quantum processing capabilities connected via lossy optical links—can distribute high-rate entanglement simultaneously between multiple pairs of users. We develop protocols for such quantum “repeater” nodes, which enable a pair of users to achieve large gains in entanglement rates over using a linear chain of quantum repeaters, by exploiting the diversity of multiple paths in the network. Additionally, we develop repeater protocols that enable multiple user pairs to generate entanglement simultaneously at rates that can far exceed what is possible with repeaters time sharing among assisting individual entanglement flows. Our results suggest that the early-stage development of quantum memories with short coherence times and implementations of probabilistic Bell-state measurements can have a much more profound impact on quantum networks than may be apparent from analyzing linear repeater chains. This framework should spur the development of a general quantum network theory, bringing together quantum memory physics, quantum information theory, quantum error correction, and computer network theory.
Quantum networks facilitate numerous applications including secure communication and distributed quantum computation by performing entanglement distribution. For some multi-user quantum applications access to a shared multipartite state is required. We consider the problem of designing protocols for distributing such states, at an increased rate. For this, we propose three protocols that leverage multipath routing to increase the distribution rate for multi-user applications. The protocols are evaluated on quantum networks with NISQ constraints, including limited quantum memories and probabilistic entanglement generation. Simulation results show that the developed protocols achieve an exponential increase in the distribution rate of multipartite states compared to single path routing techniques, with a maximum increase of four orders of magnitude for the cases studied. Further, the relative increase in distribution rate was also found to improve for larger sets of users. When the protocols were tested in scaled-down real-world topologies, it was found that topology had a significant effect on the multipartite state distribution rates achieved by the protocols. Finally, we found that the benefits of multipath routing are maximum for short quantum memory decoherence times and intermediate values of entanglement generation probability. Hence, the protocols developed can benefit NISQ quantum network control and design.
Quantum networks will enable long-distance entanglement distribution through repeater nodes capable of both generating external Bell pairs with their neighbors—independently and identically distributed (i.i.d.) with probability p—and performing internal Bell State Measurements (BSMs), which succeed with probability q. These probabilities depend on the specific experimental parameters of the network. While global link state knowledge can maximize entanglement generation rates between any two consumers, it is often impractical due to the network's dynamic nature. This work evaluates a multipath routing protocol based on local link state knowledge, designed for time-multiplexed repeaters that can perform BSMs across different time steps. We employ simulations across various network topologies to characterize how consumer placement and network topology influence the utility of dynamic and static routing strategies. Results show that increasing the time multiplexing block length, k, enhances the average entanglement generation rate, though at the cost of higher initial latency. When a step-function memory decoherence model is introduced—where qubits are stored in quantum memory for a time that follows an exponential distribution—an optimal k emerges. As p decreases or the average memory lifetime increases, this optimal k grows, reflecting a trade-off where the advantages of time multiplexing must be balanced against the heightened risk of losing previously established entangled pairs.
In this work we consider a quantum network consisting of multiple interconnected quantum repeaters. In this network, data plane of communication is achieved by photon transmission over fibre cables, while the control plane which transmits results of measurements and control information is implemented over classical Internet. Important part of the control plane is the server which distributes connection requests and entanglement resources to nodes involved in the path. Together, data and control plane establish reliable multi hop links over the network deploying purification and swapping operations. We analyze the performance of such a network using probabilistic model of communication time between repeaters, rather than slotted time. We consider random arrivals of connection requests to each repeater and variable path lengths. We model a single repeater using theory ofM[x]/G/m+rM^{[x]}/G/m+rM[x]/G/m+rqueues where each batch request encompasses heralding, purification, and swapping times pertaining to a single repeater node. To model the network, we have used the concept of Jackson's network over repeater nodes in the path. This model allows derivation of end-to-end entanglement delivery time as random distribution and calculation of probability of decoherence of qubits stored in quantum memories over the path. We considered different numbers of entanglements per request and different types of quantum memories. Results of this analysis are useful for dimensioning capacities of quantum repeaters, memories and links in order to avoid decoherence of quantum memories.
Generating and distributing entangled pairs between arbitrary nodes is essential to fully realize the network's capabilities, with the challenges of limited qubit resources, severe decoherence and stochastic physical mechanism. In this paper, we model the service process of quantum repeater nodes based on the concept of queuing theory to help characterize their availability. Further, we propose a link-disjoint multi-path routing algorithm, with repeaters' availability, nodes' qubit capacity, entangled links' fidelity and classical delay taken into consideration. The performance of our scheme has been evaluated with simulated environment and compared with other existing routing schemes.