Routing is essential for quantum communication since it controls the effectiveness, dependability, and scalability of quantum networks. Although research on routing algorithms using quantum memories has been published in the literature, there aren't any quantum memories that can simultaneously achieve high fidelity, long storage duration, wide bandwidth, multimode capacity, and high efficiency. Therefore, in this study, we developed the fidelity-guaranteed MEDIRA routing algorithm, utilizing a distributed routing approach in a memoryless quantum network. As a result of the algorithm, we achieve a throughput of 17.2 qubits per second, for a demand fixed between 1 and 20. To the best of our knowledge, this is the first work that utilizes a queuing approach in a memoryless distributed routing algorithm with fidelity assurance.
Routing is essential for quantum communication since it controls the effectiveness, dependability, and scalability of quantum networks. Although research on routing algorithms using quantum memories has been published in the literature, there aren't any quantum memories that can simultaneously achieve high fidelity, long storage duration, wide bandwidth, multimode capacity, and high efficiency. Therefore, in this study, we developed the fidelity-guaranteed MEDIRA routing algorithm, utilizing a distributed routing approach in a memoryless quantum network. As a result of the algorithm, we achieve a throughput of 17.2 qubits per second, for a demand fixed between 1 and 20. To the best of our knowledge, this is the first work that utilizes a queuing approach in a memoryless distributed routing algorithm with fidelity assurance.
Routing plays a pivotal role in quantum communication as it directly impacts the efficiency, reliability, and scalability of quantum networks. While several studies in the literature have explored routing algorithms leveraging quantum memories, current quantum memory technologies are unable to simultaneously achieve high fidelity, extended storage durations, wide bandwidths, multimode capacity, and high efficiency. To address this limitation, our study focuses on fidelity-guaranteed entanglement routing within a memoryless network architecture, employing both distributed and centralized routing approaches. Utilizing our proposed routing algorithm, MEFID, we achieved a throughput of 72 qubits per second under a fidelity threshold of 0.8 and within three iterative rounds. By integrating a purification process to ensure that the final fidelity consistently exceeds the specified threshold, our algorithm facilitates the development of robust and high-performance quantum networks.
While routing methods in the literature often assume the use of quantum memory, this study proposes a routing algorithm designed for memoryless quantum networks. The algorithm leverages lexicographic optimization principles to hierarchically prioritize and optimize multiple objectives such as distance and capacity. This approach identifies the shortest paths between source-destination pairs within the decoherence time and selects a path that satisfies the minimum capacity require ments. To prevent entanglement fidelity from dropping below the desired threshold, purification is applied. Simulation results demonstrate the algorithm’s ability to manage latency while enhancing throughput effectively. The study comprehensively analyzes performance metrics under varying capacity values, request numbers, and threshold fidelity levels. Additionally, to the best of our knowledge, it is the first study to calculate latency, including queuing delay, in the context of quantum networks. Future research aims to explore optimal threshold fidelity values that balance throughput and latency performance.
Entanglement routing selects a path to establish entanglement connections between two arbitrary nodes in quan-tum networks, which plays an important role in quantum com-munication. In quantum networks, quantum decoherence and limited network performance make it challenging to distribute entangled pairs. Many entanglement routing schemes have been proposed to solve this issue but most of them are in a centralized and synchronized manner. However, they may be infeasible in large-scale quantum networks. Therefore, in this paper, we propose a distributed and asynchronous entanglement routing scheme called DFER in which quantum nodes manage requests autonomously. The major challenge is quantum nodes have little knowledge about entangled pairs, which hinders the ability to establish fidelity guaranteed entanglement connections. To ad dress this challenge, we develop DLFR algorithm which estimates the fidelity of end-to-end entanglement connections based on link-level fidelity and calculates link-level fidelity requirement based on the characteristic of purification. Among nodes which meet link-level fidelity requirement, we design DFPS path se lection algorithm to select next hop with the highest expected throughput to distribute entangled pairs. Numerous simulation results demonstrate that DFER can efficiently distribute fidelity guaranteed entangled pairs with high throughput.
Single photons are the flying qubits of choice for distributing entanglement in a quantum internet. Quantum memories embedded in quantum repeaters are crucial to overcome transmission loss and enhance the rate of quantum communication. A multimode memory can further boost the channel capacity. However, benchmarking and building a practical quantum memory that simultaneously optimizes multiple performance metrics poses two key challenges. Here, we introduce quantum interconnect rate to comprehensively quantify quantum memories, and further demonstrate a high-performance quantum memory that simultaneously integrates three essential criteria at once: large multimode capacity, high efficiency, and high fidelity. Operating on 11-dimensional spatial modes, our memory achieves a uniform efficiency exceeding 80% and qubit storage fidelities above 99%, enabling the efficient storage of high-dimensional qudits. Based on these capabilities, we estimate a distribution of 3.56 bits of quantum information over a 1000-km repeater link in one minute, highlighting a practical pathway toward scalable quantum interconnects and quantum networks.
Future quantum networks will enable the interconnection of multiple users distributed across vast geographic distances. Due to these large separations and limited physical resources, communication will often rely on multi-path routing strategies, where physical resources are distributed across channels of varying lengths and delivered to end users. Efficient long-distance quantum communication therefore requires optimizing the allocation of these resources across available paths. In this work, we introduce a performance-oriented approach to quantum network routing by extending the classical concept of Quality of Service (QoS) to the context of multi-path quantum resources distribution. Unlike prior models that consider entanglement generation or quantum memory coherence in isolation, we investigate the interplay between path assignment strategies, coherence time constraints, and quantum error correction (QEC), and how they jointly impact end-to-end communication fidelity. We analyze both unencoded and encoded transmissions over aggregated network paths, quantifying the effects of resource allocation on transmission success. Our findings show that fidelity cannot be optimized independently of memory lifetimes, and that while QEC can enhance performance under specific conditions, it also imposes additional constraints depending on network topology and path-length asymmetries. This work provides a foundation for developing QoS-aware quantum routing protocols that balance fidelity, throughput, and memory utilization -- key considerations for near-term quantum repeater networks.
Entanglement routing establishes remote entanglement connection between two arbitrary nodes, which is one of the most important functions in quantum networks. The existing routing mechanisms mainly improve the robustness and throughput facing the failure of entanglement generations, which, however, rarely include the considerations on the most important metric to evaluate the quality of connection, entanglement fidelity. To solve this problem, we propose purification-enabled entanglement routing designs to provide fidelity guarantee for multiple Source-Destination (SD) pairs in quantum networks. In our proposal, we first consider the single S-D pair scenario and design an iterative routing algorithm, Q-PATH, to find the optimal purification decisions along the routing path with minimum entangled pair cost. Further, a low-complexity routing algorithm using an extended Dijkstra algorithm, Q-LEAP, is designed to reduce the computational complexity by using a simple but effective purification decision method. Then we consider the common scenario with multiple S-D pairs and design a greedy-based algorithm considering resource allocation and rerouting process for multiple routing requests. To verify the effectiveness and superiority of the proposed algorithms, extensive simulations are conducted, and the simulation results show that the proposed algorithms not only can provide fidelity-guarantee routing solutions, but also has superior performance in terms of throughput, fidelity of end-to-end entanglement connection, and resource utilization ratio, compared with the existing routing scheme.