Progress Report
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Scalable and Robust Integrated Quantum Communication System[4] Distributed Quantum Applications Enabled by Distributed Environments for Quantum Information
Progress until FY2025
1. Outline of the project
This year we developed a quantum application to evaluate the quantumness realized by a quantum network. This application builds on our previous theory to measure the efficacy of quantum nodes in implementing multi-node quantum operations. We also addressed application-layer server selection over the quantum internet, formulating it as a cross-layer ranking problem in which the dominant bottleneck switches among server processing, classical communication, and entanglement distribution, and proposing a lightweight telemetry-based score, Tmax, that keeps the runtime gap to the best server below 10% in simulation. We also theoretically proposed a useful application of quantum sensor networks in the field of quantum information processing. Specifically, we proposed a method for detecting oscillating magnetic fields in a quantum sensor network by entangling spatially separated solid-state qubits via photons. We showed that the correlations inherent in the entangled state enhance the detection efficiency.
2. Outcome so far
(1) This fiscal year, we focused on developing applications to evaluate how much “meaningful” quantum information processing can be achieved using the experimental resources expected to be available in the testbed targeted by this project. To this end, based on the theory we had previously developed for evaluating the efficacy of remote CNOT implementations in quantum systems composed of multiple quantum nodes and quantum links, we reexamined its underlying assumptions and assessed their consistency with the experimental resources envisioned for the project’s testbed. We then designed quantum algorithms in a manner that would maximize the feasibility of implementing these applications.
(2) Formulated quantum-internet server selection as a cross-layer ranking problem with the dominant bottleneck switching among server processing, classical communication, and entanglement distribution; proposed a lightweight runtime-prediction score, Tmax, achieving a runtime gap below 10% from the best choice in NetSquid PB-VQE evaluation, and used Sobol sensitivity analysis to identify dominant bottlenecks for deployment planning.
(3) Improved the efficiency of distillation in distributed quantum computing by analyzing the dynamics of distributed quantum sensors and processors and applying a quasiprobability method to NISQ devices, thereby proposing a low-sampling-cost way to generate entanglement between distant nodes at the expectation-value level.
(4) In our research on improving the efficiency of quantum information processing, we proposed a method for detecting oscillating magnetic fields using a photon-mediated quantum sensor network. By exploiting nonlocal correlations, we theoretically show that it enables the acquisition not only of the amplitude of the oscillating magnetic field but also of its spatial information.
3. Future plans
This fiscal year marked the final year of this project, and we expect that the achievements obtained so far will make significant contributions toward accomplishing the goals of its successor Moonshot project. In particular, the knowledge gained from distributed quantum computing can be applied to the realization and utilization of network-based quantum computers. Building on these achievements, we aim to accelerate the realization of large-scale quantum computers and thereby drive dramatic advances in society in various aspects.