A metropolitan-scale entanglement-based quantum communication network enabled by a quantum reconfigurable optical add-drop multiplexer (q-ROADM), which dynamically distributes polarisation-entangled photon pairs from a broadband source to six users over deployed campus and metropolitan fibre, is demonstrated.
Abstract
Dynamic entanglement distribution is a key requirement for scalable, multi-user and multi-protocol quantum networks. We demonstrate a metropolitan-scale entanglement-based quantum communication network enabled by a quantum reconfigurable optical add-drop multiplexer (q-ROADM), which dynamically distributes polarisation-entangled photon pairs from a broadband source to six users over deployed campus and metropolitan fibre. The network supports programmable full-mesh, partial-mesh and sliced sub-network configurations, enabling flexible allocation of entanglement resources according to link condition and service requirement. We demonstrate stable six-user full-mesh operation over more than 150 hours, compare full-mesh and time-shared partial-mesh strategies under different source and detector conditions, and realise quantum network slicing with optional/additional interconnection links. We also show that the same infrastructure can support different quantum protocols by showcasing Secure Inaugural Authentication-Transfer (SIAT) combined with Network flooding over multiple paths to improve the security of onboarding a new user. These results demonstrate a q-ROADM-enabled entanglement distribution architecture as a novel route towards reconfigurable, service-oriented quantum networking over optical fibre infrastructure.
In quantum networks, Quantum Key Distribution (QKD) and the related protocols are distributive to ensure security for end users. Also, attack detection, analyzing security vulnerabilities and performance reduction over high traffic are more challenging which is encountered at multi-user communication end. Existing approaches does not effectually overcome the above given challenges. This research proposed a novel approaches that merges conventional quantum multiple access approaches, QKD and improved security protocols for dealing these issues. Here, a novel Resource-Efficient Quantum Key Distribution (RE-QKD) for establishing communication security among diverse nodes and adopts the conventional quantum multiple accesses. It intends to offer higher speed and scalability during the communication process. Then, security is optimized with RE-QKD that relies on Quantum Access Network to optimize the queries from various end-users. The proposed RE-QKD is proposed to provide security towards the computing attacks and preventing the eavesdropping attack. The proposed model work efficiently and gives promising outcomes with its performance metrics. The proposed RE-QKD model attains 95% detection attack, 97% communication complexity, distributive key rate of 600b/s, 99% computational overhead and 97% communication efficiency. The simulation outcomes shows the reduction in communication complexity up-to 45% and improved detection accuracy which is superior compared to prevailing approaches. The proposed model helps in scalable development and quantum network with better security.
N.Saranya, S. Sasirekha· Journal of Intelligent Decis...· 0 citations
Quantum secret sharing (QSS), as a fundamental cryptographic protocol for future quantum networks, continues to face significant challenges, particularly in the generation of multipartite entanglement and the degradation of entanglement fidelity during distribution, both of which severely limit its scalability. These persistent constraints motivate an alternative approach based on continuous-variable (CV) systems. We propose a CVQSS scheme based on an electro-optically modulated optical frequency comb. The scheme employs a single laser to generate multi-wavelength coherent states, enabling the efficient and flexible construction of secret sharing subnetworks. By incorporating a broadcast-based distribution mechanism, the architecture is scalable to 128 players. Experimental verification with 24 players over a 10 km fiber link demonstrates a secret sharing rate of 6.24 per player under asymptotic conditions and 1.27 Mbps per player under finite-size effects, and a 1.05MB image is secretly shared to six players. This work achieves information-theoretically secure QSS both within and across subnetworks, providing a solid technical foundation for the development of scalable and multifunctional quantum networks.
Qijun Zhang, Yuehan Xu, Tao Wang et al.· PhotoniX· 0 citations
Quantum network implementations using single spontaneous parametric downconversion (SPDC)-based broadband entangled photon pair source (EPPS) have been reported recently. Here, leveraging the wavelength-correlation between entangled photon pairs, the traditional wavelength division multiplexing (WDM) method is utilized to route photons based on their wavelengths. From single EPPS, entangled photon pairs are distributed in a centralized way to different node pairs in the network. However, the number of nodes pairs that can be entangled in a network is limited by the number of entangled wavelength pairs that an EPPS can generate. To entangle a higher number of node pairs in a network, multiple EPPSs can be employed. In this work, we present a WDM-based entanglement distribution approach using multiple EPPSs in multi-hop repeaterless mesh optical networks. We experimentally characterize two EPPSs developed in-house and consider multiple such EPPSs in the network to perform network-level simulations. We consider heterogeneous entanglement demands requiring different entanglement bit (ebit) rates and entanglement visibility. For each entanglement demand, EPPS placement/selection, wavelength-pair assignment, and photon pair routing are performed considering the degradation in both ebit rate and visibility with fiber length and hops in the network. Two main findings of this study include: (i) a hybrid approach of one-photon (OP) and both-photon (BP) entanglement distribution provides higher flexibility in multi-EPPS placement and (ii) distributed entanglement distribution using multiple EPPSs enables better entanglement resource utilization and higher entanglement demand acceptance as compared to centralized entanglement distribution.
Anuj Agrawal, A. Dulta, Bhaskar Kanseri· 0 citations
As practical quantum networks approach large-scale deployment, the need for efficient user-to-user frequency allocation is increasing, yet current approaches only provide partial solutions to the routing and spectrum allocation problem for an arbitrary quantum network. We address this challenge for repeater-less flex-grid quantum networks based on hyperentangled photons using an efficient three-stage pipeline combining leading tools in classical networking with recent advances in numerical optimization. First, double instantiations of Yen's algorithm obtain low-loss route candidates between each pair of users and the entanglement sources. Second, the advanced process optimizer (APOPT) obtains frequency channel allocations that maximize distribution rates under fidelity constraints. Finally, the constraint programming solver using satisfiability methods (CP-SAT) assigns specific frequency bins to each link, ensuring that there is no contention between frequencies from different sources. We numerically demonstrate this approach on a representative ring network and a Manhattan incumbent local exchange carrier topology, realizing significant improvements over prior genetic algorithm approaches in speed, accuracy, and scalability. Overall, this pipeline provides an efficient heuristic workflow for optimizing broadband entanglement distribution, applicable to arbitrarily connected quantum networks integrated within the existing lightwave infrastructure.
Zachary Goisman, M. L. Stevens, Maxwell Goisman et al.· 0 citations
Introduction: Continuous-variable quantum teleportation and entanglement distribution are fundamental building blocks for future quantum internet infrastructures. Quantum passive optical networks (QPONs) provide a promising architecture for scalable multi-user quantum communication by exploiting the mature passive optical network infrastructure.
Materials and methods: We develop a theoretical framework for continuous-variable entanglement distribution and quantum teleportation in QPONs using two-mode squeezed vacuum states propagating through splitter–combiner–loss channels. Both downlink and uplink architectures are investigated under assisted and non-assisted protocols. The performance is analyzed using covariance matrix formalism, logarithmic negativity, and teleportation fidelity, and closed-form analytical expressions are derived together with numerical evaluations.
Results: The analysis demonstrates that downlink entanglement distribution consistently outperforms the uplink architecture in terms of both logarithmic negativity and teleportation fidelity except in noise-less channels. Assisted protocols further enhance the achievable performance compared with non-assisted schemes. We derive the optimum squeezing parameter for non-assisted teleportation, showing that excessive squeezing may become detrimental because of network loss and splitting. Numerical results quantify the effects of network size, transmission distance, channel excess noise, detector imperfections, and measurement-added noise on entanglement distribution and teleportation performance. Also, we have showed that the time-division multiple-access is the preferred scheduling scheme between the users.
Conclusions: The proposed framework establishes fundamental performance limits for continuous-variable QPONs and identifies practical design guidelines for scalable quantum access networks. The results demonstrate the advantages of downlink entanglement distribution and assisted teleportation, providing theoretical support for the development of future multi-user quantum communication and quantum internet infrastructures.
Amir Mohammad Yaghoobianzadeh, J. Salehi· Academia Quantum· 0 citations
Quantum Fair Exchange (QFE) is a critical primitive for secure multi-party cooperation in the emerging distributed Quantum Internet. However, extending QFE to cross-domain scenarios remains challenging. Existing schemes typically rely on centralized Bell State Measurements (BSM) during the fair-exchange phase, which impose stringent hardware and synchronization requirements and become difficult to deploy in wide-area settings due to transmission latency, quantum decoherence, and photon loss. To address these barriers, we propose a practical cross-domain QFE protocol based on Functional Decoupling and Reconstruction. Instead of performing demanding joint measurements on user-encoded quantum states, the proposed protocol decouples the required correlation-extraction functionality into distributed Z-basis measurements and classical result reconstruction. Thus, it obtains the information required by the fair-exchange rule without relying on centralized BSM in the fair-exchange phase, thereby simplifying physical implementation and improving cross-domain feasibility. We analyze the correctness, fairness, security, and efficiency of the proposed protocol under the stated assumptions, and compare its measurement requirements with those of conventional QFE designs. We further validate the core reconstruction logic on real superconducting and NMR quantum processors, and analyze the impact of representative noise models under different encoding strategies and noise regimes. The analytical, experimental, and simulation results show that the proposed scheme preserves the intended fair-exchange functionality while reducing engineering requirements, and that encoding selection affects protocol success under device-specific noise conditions.
Yinghua Jiang, Liquan Chen, Yaqing Zhu et al.· IEEE Transactions on Green C...· 0 citations