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arXiv:2507.13999 · IEEE International Conference on Quantum Computing and Engineering (QCE)

The Proportional Fair Scheduler in Wavelength-Multiplexed Quantum Networks

Sanidhay Bhambay, Siddarth Koduru Joshi, Thirupathaiah Vasantam, Neil Walton

Published Aug 30, 2025• 0 citations
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Abstract

We address the problem of optimal pumping strategies in quantum networks. These networks enable secure communication by distributing entangled photon pairs to user (or node) pairs. Quantum Key Distribution (QKD) protocols, like BBM92, generate secret keys from entangled photons. While secure communication and error correction are essential for any quantum communication channel, resource contention, optimization, and fairness issues are critical for networks. In this article, we analyze the performance of quantum networks, proposing simple distributed algorithms for QKD networks generating secret keys. There are significant advantages of pumping entangled photons in QKD networks, but challenges arise in practical implementations. The underlying channels are inherently time-varying, and thus data rates fluctuate between nodes. Moreover, multiple edges (node pairs) can be pumped simultaneously, albeit at the cost of a reduced secret key rate (SKR). These temporal and spatial constraints yield a complex decision-making problem whose solutions may favor a small set of user pairs to the detriment of overall, long-run network performance. We design adaptive pumping strategies that address these challenges in QKD networks. In particular, we find that a proportional fairness pumping strategy (PF-PS) stands out by dynamically prioritizing users with lower average secret key rates and optimally balancing fairness with throughput. The proposed algorithm is a natural extension to quantum networks of the Proportional Fair Scheduler deployed in 4G LTE and 5G mobile networks. Both theoretical analysis and numerical simulations confirm that PF-PS is optimal for entangled state distribution, and thus, when adapted appropriately, proportional fair pumping is a strong candidate for efficient resource allocation in quantum networks.

DOI
10.1109/qce65121.2025.00140

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We address the problem of optimal pumping strategies in quantum networks. These networks enable secure communication by distributing entangled photon pairs to user (or node) pairs. Quantum Key Distribution (QKD) protocols, like BBM92, generate secret keys from entangled photons. While secure communication and error correction are essential for any quantum communication channel, resource contention, optimization, and fairness issues are critical for networks. In this article, we analyze the performance of quantum networks, proposing simple distributed algorithms for QKD networks generating secret keys. There are significant advantages of pumping entangled photons in QKD networks, but challenges arise in practical implementations. The underlying channels are inherently time-varying, and thus data rates fluctuate between nodes. Moreover, multiple edges (node pairs) can be pumped simultaneously, albeit at the cost of a reduced secret key rate (SKR). These temporal and spatial constraints yield a complex decision-making problem whose solutions may favor a small set of user pairs to the detriment of overall, long-run network performance. We design adaptive pumping strategies that address these challenges in QKD networks. In particular, we find that a proportional fairness pumping strategy (PF-PS) stands out by dynamically prioritizing users with lower average secret key rates and optimally balancing fairness with throughput. The proposed algorithm is a natural extension to quantum networks of the Proportional Fair Scheduler deployed in 4G LTE and 5G mobile networks. Both theoretical analysis and numerical simulations confirm that PF-PS is optimal for entangled state distribution, and thus, when adapted appropriately, proportional fair pumping is a strong candidate for efficient resource allocation in quantum networks.
Abstract Quantum networks provide both security and faster communication; however, they face critical challenges in terms of dynamic resource allocation and maintaining robust security. Current static allocation methodologies frequently lead to excessive latency and attack vulnerabilities, which restrict performance and scalability. To address these challenges, this article presents a secure and adaptive resource allocation outline for quantum networks, merging quantum-enhanced security protocols with real-time optimization. The framework utilizes Quantum Key Distribution - Single Center Method (QKD-SCM) to exchange secure and scalable keys. and the Stochastic Programming and the Cooperative-Qubit-Allocation-Problem (SP-CQAP), which addresses dynamic resource allocations. High-fidelity entangled resources are managed with the Fidelity Maintenance Scheme Based on Prioritized Purification (FMSPP), and congestion is avoided using Self-Adaptive and Content-Based Scheduling (CACS). The proposed framework was evaluated using NS-3.30.1 and Python 3.7.4, running on Ubuntu 18.4 LTS. In comparison to already-existing methodologies within the segment, the proposed framework demonstrated reduced latency of 20 ms, energy efficiencies of 90%, a quantum key distribution success rate of 90%, and resource utilization equating to 70%. The findings demonstrate the promise of quantum-enhanced wireless communication through dynamic resource allocation for safe, low-latency, and high-performance networking. Removed: security enhancement implied earlier.
Quantum key distribution (QKD) uses the laws of quantum mechanics to distribute secret keys with information-theoretic security. To realize QKD for secure communications among multiple distant users, fiber-based QKD networks can be deployed with today's available technologies. Incorporating QKD into existing wavelength-division multiplexing (WDM) network infrastructure provides a practical way to reduce the difficulty and cost of QKD networking. Nonetheless, the costs of QKD nodes and QKD links are still considered as the major barriers to long-distance QKD network deployment in practice. In this work, we study how to minimize the cost of deploying QKD-over-WDM backbone networks. We introduce a general architecture of QKD-over-WDM backbone networks. A novel cost-oriented model is defined to elaborate the cost-minimized problem, in which various QKD network components including QKD transceivers, QKD auxiliary equipment for QKD backbone nodes and trusted repeater nodes (TRNs), and QKD links are considered. The physical-layer parameters such as secret-key rate, physical distance, and the layout of TRNs are also incorporated in our defined model. We develop an integer linear programming (ILP) model and a novel cost-efficient QKD networking (CEQN) heuristic algorithm to address the cost-minimized problem. The extensive simulations indicate that our proposed approaches are effective in reducing the cost of deploying QKD-over-WDM backbone networks, where the designed CEQN algorithm is efficient to demonstrate similar to the ILP model. Finally, some open issues in future work are discussed, given that this work only presents an early highlevel analysis as opposed to a definitive detailed model.
Quantum key distribution (QKD) networking over wavelength-division multiplexing (WDM) network infrastructure provides a new paradigm for secure communications across the networks. With limited wavelength resources in existing WDM networks, how to efficiently schedule QKD to provision sufficient secret keys over WDM networks becomes a new challenge. This study proposes a new time-scheduled scheme in combination with quantum key pool (QKP) technique to overcome this challenge. A new architecture of QKD-over-WDM networks is presented, in which QKPs are constructed to decouple secret-key resources from the underlying infrastructure for timely secret-key provisioning. In the time-scheduled scheme, routing, wavelength, and time-slot allocation (RWTA) problem is proposed for efficient QKP construction (QKPC) over WDM networks, in which three sub-problems (i.e., secret-key consumption, time-slot allocation, and time-slot continuity) are discussed, respectively. An integer linear programming (ILP) model and a novel joint path-and-link-based RWTA (JPL-RWTA) heuristic algorithm are designed to solve the RWTA problem, in which the three sub-problems are addressed together. Simulation results indicate that the ILP model and JPL-RWTA algorithm are effective approaches to obtain the positive balance between resource utilization of QKPC and successful probability of QKPC (SPQKPC). Moreover, the SPQKPC can be increased at the cost of reducing the flexibility of secret-key consumption, the uniformity of time-slot allocation, and the proportion of time-slot continuous QKPC to time-slot discrete QKPC requests.
Satellite-based quantum key distribution (QKD) systems use constellations of satellites to assist secret key generation among ground station pairs that are far away from each other. In this paper, we study satellite scheduling to establish secret keys among ground station pairs in a fair and efficient manner. While satellite scheduling has been considered in the past, existing scheduling algorithms are not for QKD, and have not explicitly accounted for fairness of resource allocation among ground station pairs. We propose three satellite scheduling strategies that have different tradeoffs in fairness and computational overhead. Using extensive simulation, we evaluate these strategies in a wide range of settings, while considering realistic environmental conditions (time-of-day, cloud coverage). Our results demonstrate that they achieve significantly better fairness at the cost of slightly lower overall number of keys when compared to a baseline strategy that has no fairness considerations.
Quantum key distribution (QKD) enables two parties to establish a secret key over a potentially hostile channel by exchanging photonic quantum states, relying on the fact that it is impossible for an eavesdropper to tap the quantum channel without disturbing these photons in a way that can be detected [1]. Here we introduce a large-alphabet QKD protocol that makes optimal use of temporal and spectral correlations of entangled photons, reaching the maximum number of inde- pendent basis states (the Schmidt number) and enabling extremely high information content per photon together with an optimal rate of secret key generation. This protocol, which we call 'Dense Wavelength Division Multiplexed Quantum Key Distribution' (DWDM-QKD), derives its security by the conjugate nature of the temporal and spectral entanglement of photon pairs generated by spontaneous parametric down conversion. By using a combination of spectral and temporal bases, we can adjust the protocol to be resource efficient. We show that DWDM-QKD is well suited to approach the optimal key generation rate using present-day sources, detectors, and DWDM opti- cal networks from classical communications, as well as emerging optical interconnect and photonic integrated chip (PIC) systems.
A fully connected quantum network with a wavelength division multiplexing architecture plays an increasingly pivotal role in quantum information technology. With such architecture, an entanglement-based network has been demonstrated in which an entangled photon-pair source distributes quantum entanglement resources to many users. Despite these remarkable advances, the scalability of the architecture could be constrained by the finite spectrum resource, where O(N^2)wavelength channels are needed to connect N users, thus impeding further progress in real-world scenarios. Here, we propose an optimized scheme for the wavelength division multiplexing entanglement-based network using a state-multiplexing quantum light source. With a dual-pump configuration, the feasibility of our approach is demonstrated by generating state-multiplexing photon pairs at multiple wavelength channels with a silicon nitride microring resonator chip. In our demonstration, we establish a fully connected graph between four users with six wavelength channels - saving half of which without sacrificing functionality and performance of the secure communication. A total asymptotic secure key rate of 1946.9 bps is obtained by performing the BBM92 protocol with the distributed state. The network topology of our method has great potential for developing a scalable quantum network with significantly minimized infrastructure requirements.