Abstract: Commercial quantum key distribution (QKD) systems are currently very expensive and usually come as large server rack components. Thus, their application is still very limited and adoption in practical implementations has not happened yet. One reason for the high price and large size is the use of high-end and custom-built hardware. We present for […]
Abstract: The violation of Bell-like inequalities unambiguously verifies the entanglement of a multipartite quantum state. However, experimental impairments and nonidealities often compromise the entanglement quality, and this degradation translates into a non-maximal violation of these inequalities. We present a detailed analysis of the influence of experimental impairments on the quality of nonlocal polarization entanglement for […]
Abstract: We study Bayesian decoding of finite-energy Gottesman–Kitaev–Preskill (GKP) qubits from multi-shot homo dyne records under coherent displacement channels, in which all shots of a trial share one latent shift. Our first contribution is an α-marginalised Bayes-optimal decoder, validated shot-for shot against the exact likelihood computed from the simulator’s own wavefunction/Fock pipeline: the textbook IID […]
Abstract: This work presents a novel micromachined, seamless sapphire–silicon hybrid evanescent-mode cavity architecture incorporating selectively engineered coupling channels and flux-tunable external coupling via a SQUID. The proposed design enables two simulated operating states within a single device: an ultra–high Q memory configuration and a high-speed readout configuration with intrinsic Purcell filtering, which is expected to […]
Abstract: Layered architectures for the Quantum Internet have been proposed, inspired by that of the classical Internet, which has demonstrated high maintainability even in large-scale systems. While lower layers in the Quantum Internet, such as entanglement generation and distribution, have been extensively studied, the application layer — responsible for translating user requests into executable quantum-network […]
Abstract: QKD technology is being increasingly adopted inside the network core for protecting information transport against any form of computational attacks. However, the use of QKD for wide-area internetworking is still challenging and costly, due to its strong trust assumptions and the low achievable key rates in long QKD links. This paper presents a standards-driven […]
Abstract: Twin-field quantum key distribution (TF-QKD) relies on first-order interference between coherent optical fields combined at an intermediate station, which requires simultaneous phase and polarization stabilization. We present a Sagnac-like interferometric architecture arranged in a hybrid star–bus network topology that enables any-to-any connectivity while providing passive stabilization of phase and polarization fluctuations for multiple wavelengths. […]
Abstract: Ansatz selection is a key factor in the performance of variational quantum algorithms (VQAs). While much of the state-of-the-art still relies on heuristic choices, an inadequate circuit structure can compromise both the expressive power and the trainability of the resulting model. Recent results have also established theoretical connections between expressibility and the onset of […]
Abstract: Practical NV-center magnetometry requires both accurate modeling of open quantum dynamics and robust control under environmental drift. However, commonly used perturbative descriptions inadequately capture dissipative processes, while existing control strategies remain individually limited: open-loop protocols cannot adapt to unknown frequency variations, Lyapunov feedback typically converges only to a neighborhood of the optimal sensing state, […]
Abstract: We have investigated the entanglement distribution and quantum teleportation in quantum passive optical networks (QPONs), where an entangled state is distributed between the central node and multiple end users through lossy fibers and passive optical splitter/combiner. The entanglement degradation is quantified using logarithmic negativity, and teleportation fidelity both in non-assisted and assisted strategies. We […]