Quantum Information Processing最新文献

Quantum Key Distribution (QKD) provides information-theoretic security, yet its practical deployment is strongly constrained by channel noise, timing uncertainty, and vulnerability to synchronization disturbances, particularly in noisy intermediate-scale quantum (NISQ) systems. This paper proposes a synchronization-aware QKD protocol in which timing estimation and key generation are explicitly integrated at the protocol level. The scheme embeds frame-level clock offset estimation, time-domain detection filtering, and adaptive coincidence-window control directly into the QKD workflow, allowing synchronization quality to directly govern key acceptance. The protocol operates on discrete, time-tagged single-photon detection events and does not rely on continuous pulse assumptions. Timing uncertainty arising from detector jitter and bounded adversarial delay is reflected in the synchronization acceptance probability and contributes explicitly to the quantum bit error rate (QBER). A hybrid simulation framework combining NetSquid-based quantum-layer modeling with event-driven classical control is used to evaluate protocol performance under realistic detector and channel parameters. Simulation results demonstrate that adaptive detection-window control effectively mitigates performance degradation due to timing jitter and bounded delay attacks, maintaining positive finite-key secure key rates and fidelity above (97%) under realistic operating conditions. Comparative evaluation against BB84, E91, Twin-Field QKD, and High-Dimensional QKD indicates improved tolerance to timing uncertainty and adversarial delay without modifying the underlying QKD primitives. These results highlight the importance of synchronization-aware design for robust QKD operation and support the feasibility of the proposed approach in practical quantum communication networks.

One of the key challenges in building a robust quantum network is the efficient distribution of entanglement and mitigating the detrimental effects of noise, which limit the information transmission rate of quantum channels. In this work, we address these challenges by utilizing the superposition of trajectories and indefinite causal orders. We demonstrate that the effects of amplitude damping can be mitigated using a bit-flip channel, while phase damping can be countered with phase-flip noise. Additionally, depolarizing noise can be suppressed using a bit-phase flip channel. Our results show that at lower noise levels, a coherent superposition of channels is more effective, whereas at higher noise levels, a quantum switch implementing indefinite causal order provides better performance. We compute the quantum capacity of channels in both indefinite causal order and coherent superposition scenarios, revealing that coherent control over quantum channels and indefinite causal order can significantly enhance channel capacity compared to a single application of the channel.

The diverse landscape of quantum computing modalities and software frameworks poses significant challenges for evaluating performance across a range of computational tasks and applications. Benchmarking procedures for quantum computers are often intricate and difficult to reproduce for end-users, quantum algorithm developers, and quantum resource providers. This challenge is compounded by the emergence of analog, non-universal approaches to quantum information processing, including quantum annealers, boson samplers, and quantum simulators. Recent advances in quantum computing technology underscore the increasing need for well-defined, comprehensive, and standardized methods for performance benchmarking. This paper introduces an open and modular software framework to enhance the reproducibility and execution of quantum benchmarking experiments. The core utility of the framework lies in enabling seamless, standardized execution of benchmarks across diverse quantum computing modalities—including gate-based, photonic, and annealing QPUs—at various levels of the quantum-classical stack. As a practical demonstration of current capabilities, we present a novel methodology to deploy an application-driven benchmarking suite. To the best of our knowledge, no other benchmarking framework attempts to cover all three described modalities across different benchmarking levels. While some approaches enable such comparisons at a certain level, these analyses often do not provide a complete picture and must be complemented with additional and hardware specific metrics. Our framework, based on a curated set of representative problems for different user communities, is executed at both the circuit level and the hybrid classical-quantum level to provide a comprehensive assessment of quantum system performance. Finally, we propose an approach for analyzing performance results using multiple-criteria decision analysis (MCDA), which allows us to incorporate different performance metrics into a unified decision-making process that supports more transparent and interpretable benchmarking results.

Modular and networked quantum architectures can scale beyond the qubit count of a single device, but executing a circuit across modules requires implementing non-local two-qubit gates using shared entanglement (ebits) and classical communication, making ebit cost a central resource in distributed execution. The resulting distributed quantum circuit (DQC) problem is combinatorial, motivating prior heuristic approaches such as hypergraph partitioning. In this work, we decouple module allocation from distribution. For a fixed module allocation (i.e., assignment of each qubit to a specific quantum processing unit), we formulate the remaining distribution layer as an exact binary integer programming (BIP). This yields solver optimal distributions for the fixed allocation subproblem and can be used as a post-processing step on top of any existing allocation method. We derive compact BIP formulations for four or more modules and a tighter specialization for three modules. Across a diverse benchmark suite, BIP post-processing reduces ebit cost by up to 20% for random circuits and by more than an order of magnitude for some arithmetic circuits. While the method incurs offline classical overhead, it is amortized when circuits are executed repeatedly.

Quantum computing offers the potential for exponential speed-ups for classically intractable problems, yet quantum programming is still susceptible to bugs. Classical debugging methods are often inadequate, as quantum mechanical principles make state inspection disruptive and classical simulation has exponential time complexity. This survey explores the landscape of quantum assertions as a key technique for identifying and locating bugs in quantum programs. We classify these techniques into two primary categories based on their evaluation stage: classical runtime and quantum runtime assertions. For each category, we analyze the strengths, limitations, time complexity, and applicability of current methods. Our findings show that scalable quantum debugging remains an open problem—a challenge that will persist even with the advent of fault-tolerant hardware. Finally, this work highlights key challenges and proposes future directions for the development of novel quantum debugging techniques.

Quantum resource theories (QRTs) provide a versatile framework for quantifying and manipulating quantum resources, with widespread applications in quantum communication, computation, and information processing. While the (epsilon )-D version of resource measures has been previously studied, its applicability has been largely restricted to addressing experimental imperfections. To tackle broader challenges such as adversarial interference and probabilistic noise, this paper introduces three novel approaches: the (delta )-(mathcal {T}) version and two weighted integral versions. These measures extend the robustness framework of QRTs, enabling a more comprehensive evaluation of quantum resource resilience under realistic conditions. We rigorously analyze their theoretical properties, including non-negativity, monotonicity, convexity, asymptotic continuity, and monogamy, demonstrating their robustness and versatility. As applications to resource dilution protocols, we establish these measures as fundamental lower bounds for resource costs, showcasing their practical relevance in the design of resilient quantum protocols. This work provides fresh insights into resource quantification within QRTs and offers strong theoretical support for secure and reliable quantum communication and computation protocols.

Constacyclic BCH codes, as a generalization of BCH codes, have been widely used in the construction of quantum codes. In this paper, we mainly study narrow-sense Hermitian dual-containing constacyclic BCH codes over (mathbb {F}_{q^2}) of new length (n=frac{q^{2m}-1}{a(q+1)}), where q is a prime power, (m ge 3) is an odd integer and (a ne 1) is a divisor of (q-1), as well as of length (n=frac{2(q^m+1)}{q+1}), where q is an odd prime power and (m ge 3) is odd. Firstly, we present some necessary and sufficient conditions for these constacyclic BCH codes to be Hermitian dual-containing. Secondly, the explicit dimensions of these constacyclic BCH codes are completely determined. Furthermore, some quantum codes with new parameters are constructed by these Hermitian dual-containing constacyclic BCH codes.

High-dimensional multipartite entanglement plays a central role in high-capacity anti-noise quantum communication and quantum computation fields. In the paper, we propose a practical preparation protocol for four-photon three-dimensional spatial-path GHZ state with spontaneous parametric down-conversion (SPDC) sources and non-ideal photon detectors. Our preparation protocol is highly feasible under current experimental conditions. The SPDC source and the non-ideal photon detectors would introduce disturbed items into the output quantum state and reduce the fidelity of the target three-dimensional spatial-path GHZ state to about 0.09. By adopting the quantum non-demolition detection on two of the four output modes, one can eliminate most of the disturbed items and increase the fidelity to about 3/7. Our protocol can provide a theoretical guidance for the experimental preparation of the high-dimensional spatial-path GHZ state and has application potential in future quantum communication and computation field.

Continuous-time quantum walks (CTQWs) provide a versatile framework for exploring quantum transport on graphs. In this work, we investigate how the introduction of edge-weight modulation at a single vertex can suppress its occupation probability. We show that when the edges connected to the root vertex are enhanced by a factor J, the probability of detecting the walker at this vertex decays as (1/J^2), provided the initial state has no components on the vertex itself or its nearest neighbors. We derive the full eigenvalue and eigenvector structure of this system, revealing that the suppression arises from the decoupling of two symmetric line subgraphs and the destructive interference of higher-order contributions. The analysis is extended to tree graphs, where we demonstrate the same scaling behavior and identify the role of local graph geometry in controlling vertex probabilities. These results suggest edge-weight modulation as a mechanism for manipulating transport pathways in CTQWs, with potential applications in quantum information transfer and state engineering, and may serve as a probe of decoherence effects in open quantum systems.

On the basis of the five-qubit entangled state introduced by Briegel and Raussendorf (Phys. Rev. Lett. 86: 910, 2001), we propose a tripartite scheme for remotely sharing an arbitrary single-qubit operation. Unlike some existing quantum operation schemes, this scheme is distinguished by an arbitrary rather than a restricted shared operation; a deterministic rather than a probabilistic chance of final success; local rather than nonlocal necessary operations; and a relatively high intrinsic efficiency. Additionally, the essential operation functions, the physical mechanisms, and the security of the scheme are analyzed and confirmed comprehensively. Furthermore, the impact of phase-damping noise on our scheme is analyzed via fidelity. Investigation shows that the proposed scheme is fully realizable with currently available experimental technologies.