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.

With the increasing security demands of nextgeneration communication standards and the looming threat posed by quantum computers to traditional encryption methods, quantum key distribution (QKD) has emerged as a promising solution in domains such as military, government, and finance, with significant potential for further commercialization. Although QKD is theoretically unconditional secure, practical implementations often face vulnerabilities arising from imperfections in channels and devices, as well as inherent characteristics of QKD protocols. This paper investigates the probability of eavesdropping from the perspective of error rates using probabilistic analysis. Such an approach not only facilitates the detection of potential eavesdropping but also helps estimate the amount of leaked information, providing a basis for subsequent countermeasures like privacy amplification. Additionally, the probabilistic analysis sheds light on the robustness of communication channels with varying quality against eavesdropping attempts.

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.

The application of hybrid scheduling for both conventional data transmission and quantum key distribution (QKD) in next-generation hybrid 6G networks is examined in this research. The study simulates transmission over Multimode Fiber (MMF), where QKD keys and classical packets are sent in parallel without a scheduler, and over Single-Mode Fiber (SMF) utilizing time-based and event-based scheduling protocols. Bit Error Rate (BER) and Packet Error Rate (PER) comparisons between the two protocols show improvements in latency and resource allocation efficiency achieved by the SMF scheduler. Concurrent transmission of classical and quantum offers the possibility of boosting data throughput. The effect of cross-talk coefficient on the accuracy of transmitted data is also elaborated. These findings highlight the necessity for customized methods in hybrid quantum-classical networks by shedding light on the performance and adaptability of scheduling techniques on SMF and the advantages of space division multiplexing on MMF. For MMF specifically it showcases noise resistance quantum data transmission.

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.