Quantum Information Processing最新文献

{"title":"Development process towards a cost-effective single-photon detector","authors":"Rory Pentz,&nbsp;Simphiwe Makhathini,&nbsp;Letsie Mofokeng,&nbsp;Kessie Govender","doi":"10.1007/s11128-026-05283-1","DOIUrl":"10.1007/s11128-026-05283-1","url":null,"abstract":"<div><p>This study explores advancements in the design of single-photon detectors (SPDs) by first reviewing conventional development approaches. The performance of avalanche photodiodes (APDs) was systematically investigated across varying reverse bias voltages, operating temperatures, and passive quenching resistances, providing new insights into their suitability as sensors for SPD applications. The focus of this work was to identify the most cost-effective APD for reliable single-photon detection. Notably, substituting bipolar junction transistors with an operational amplifier (op-amp) as the first-stage amplifier simplified the design. In addition, a comparative evaluation of the traditional transimpedance amplifier configuration and a voltage amplifier revealed that the latter significantly increased the first-stage gain. We investigated the detection limits of the single-photon detectors by attenuating the excitation laser with neutral density filters. Collectively, these methodological refinements enabled the system to achieve photon-counting approaching single-photon events, underscoring its potential for practical and economical SPD implementation.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11128-026-05283-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the efficacy of quantum ML: QSVM and QNN on IBM simulators","authors":"Vikesh Yadav,&nbsp;Savita Kumari Sheoran,&nbsp;Rakesh Kumar Sheoran","doi":"10.1007/s11128-026-05270-6","DOIUrl":"10.1007/s11128-026-05270-6","url":null,"abstract":"<div><p>Quantum Machine Learning (QML) represents a frontier in computational intelligence, leveraging quantum mechanics to enhance data-driven learning paradigms. This study systematically evaluates the efficacy of two quantum machine learning algorithms-Quantum Support Vector Machine (QSVM) and Quantum Neural Networks (QNN) on IBM quantum simulation platforms. Utilising the Aer Simulator, Qasm Simulator and Statevector Simulator, the algorithms are benchmarked across six diverse datasets: Iris, Wine, Breast Cancer, Rain, Indian Liver Patient and Banknote Authentication. To accommodate the qubit limitations of current quantum systems, feature dimensionality is optimised through Principal Component Analysis (PCA) while preserving the majority of data variance. Performance is evaluated using accuracy, precision, recall, F1-score, training loss and execution time. In addition, classical machine learning models, including Support Vector Machine, Decision Tree, k-Nearest Neighbour and Multi-Layer Perceptron are employed as baseline classifiers using the same preprocessing pipeline and feature space. Experimental results demonstrate that the performance of quantum models is highly dataset-dependent, with competitive results achieved on selected complex datasets where the performance of classical models degrade while classical approaches generally exhibit superior accuracy and computational efficiency on low-dimensional benchmark problems. The findings provide a comprehensive assessment of QSVM and QNN under current Noisy Intermediate-Scale Quantum (NISQ) constraints and contribute to understanding the practical applicability and limitations of quantum machine learning in near-term quantum environments.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Swapped entanglement in high-dimensional quantum systems","authors":"S. M. Zangi,&nbsp;Chitra Shukla,&nbsp;Khalid Naseer,&nbsp;Saeed Haddadi","doi":"10.1007/s11128-026-05289-9","DOIUrl":"10.1007/s11128-026-05289-9","url":null,"abstract":"<div><p>Entanglement swapping is a fundamental protocol in quantum information processing that enables the distribution of entanglement between distant quantum systems and plays a central role in quantum communication networks. In this work, we investigate entanglement swapping in arbitrary-dimensional quantum systems (qudits) and provide a quantitative analysis of the resulting entanglement distribution. Using I-concurrence and negativity as entanglement measures, we derive and analyze the average swapped entanglement generated by generalized Bell-state measurements. Our results show that increasing the system dimension enhances the efficiency of entanglement distribution, with high-dimensional systems exhibiting superior performance compared to their qubit counterparts. We further examine the implications of high-dimensional entanglement swapping for long-distance quantum communication and teleportation protocols relevant to quantum repeater architectures. In addition, we study the effects of noise by considering mixed entangled qudit states and analyze the behavior of the swapped entanglement as a function of fidelity and system dimension. The results demonstrate that higher-dimensional systems provide improved robustness against noise, highlighting their potential advantages for future quantum communication technologies.\u0000</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148614006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reversible imprinting and retrieval of quantum information: experimental verification of the Quantum Memory Matrix hypothesis","authors":"Florian Neukart,&nbsp;Eike Marx,&nbsp;Valerii Vinokur","doi":"10.1007/s11128-026-05292-0","DOIUrl":"10.1007/s11128-026-05292-0","url":null,"abstract":"<div><p>We report a hardware implementation of a reversible imprint-retrieval cycle motivated by the Quantum Memory Matrix (QMM) framework. Using IBM Quantum backends, we realize five circuits that scale from a minimal three-qubit memory cell to a five-qubit dual-cycle architecture, including variants with controlled phase evolution and deliberate perturbation. Because the circuit readout is based on computational-basis bit strings, the primary experimental metric is the basis-matched retrieval probability, <span>(P_{textrm{ret}}=N_{textrm{match}}/N_{textrm{shots}})</span>, reported together with Wilson-score <span>(95,%)</span> confidence intervals, Pearson correlations, and mutual information between field and output qubits. Across the five experiments, <span>(P_{textrm{ret}})</span> ranges from <span>(0.487pm 0.017)</span> in the evolution stress test to <span>(0.732pm 0.012)</span> in the baseline three-qubit cycle, with the dual-cycle and controlled-error variants remaining near 0.70 under realistic device noise. These results provide a proof-of-principle demonstration that finite-dimensional quantum registers can store and return basis-level information through local unitary gates. The experiments therefore support the operational imprint-retrieval primitive underlying QMM, while also identifying full state tomography as the next step toward verifying phase-coherent state recovery.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11128-026-05292-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential-quadrature-phase-shift quadruplet-field quantum key distribution","authors":"Kyo Inoue,&nbsp;Toshimori Honjo","doi":"10.1007/s11128-026-05277-z","DOIUrl":"10.1007/s11128-026-05277-z","url":null,"abstract":"<div><p>A quantum key distribution (QKD) scheme that works over long distances is proposed wherein two parties aiming to share a secret key send quantum signals to an intermediary party. The system configuration is similar to twin-field (TF) QKD, but lasting sequential weak coherent pulses are transmitted instead of single pulses and a delay interferometer is used to receive the transmitted pulses instead of a beam splitter. With these modifications, four pulses interfere with each other at the intermediary party, which prohibits that party from eavesdropping by directly measuring the transmitted signals. The proposed protocol does not include phase randomization or decoy methods, and thus the system setup and operation are simpler than in conventional TF-QKD while achieving similar QKD distances.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reflection-based semiquantum key distribution protocols using half of raw key bits for security checks","authors":"Wenchen Tan,&nbsp;Xiangfu Zou,&nbsp;Xinting Su,&nbsp;Minghui Cai","doi":"10.1007/s11128-026-05275-1","DOIUrl":"10.1007/s11128-026-05275-1","url":null,"abstract":"<div><p>Semiquantum key distribution (SQKD) enables two remote users to establish a confidential key, even against an adversary with unbounded computational power. In an SQKD protocol, one user is called classical user who is restricted to preparing and measuring quantum states in the computational basis. Recently, a novel and interesting reflection-based semiquantum key distribution (RB-SQKD) protocol was proposed, where the classical user’s reflection operations directly contribute to key generation. Security and efficiency are two critical criteria for evaluating SQKD protocols. Standard quantum key distribution (QKD) and SQKD protocols check security by sacrificing raw key resources, typically consuming either half of the raw key or half of the rounds, including potential key-generating rounds. In contrast, the original RB-SQKD protocol performs security checks only on the non-key-generating rounds, resulting in a distinct trade-off between security and efficiency. To unify the security-check mechanism with those of standard QKD and SQKD protocols, this paper proposes two modified RB-SQKD protocols, Protocol 1 and Protocol 2, wherein half of the rounds are randomly selected for security checks, including potential key-generating rounds. Despite sacrificing half of the raw key bits for testing, both protocols maintain an efficiency above <span>(50%)</span> of the original: Protocol 1 attains <span>(frac{2}{3})</span> of the original protocol’s efficiency, while Protocol 2 preserves the original efficiency. Specifically, Protocol 1 introduces two key modifications: optimizing the classical user’s random operation probabilities and eliminating all auxiliary quantum states. Meanwhile, Protocol 2 enhances efficiency by reusing previously non-key-generating rounds for key generation. These modifications yield substantial efficiency improvements. In addition, this paper provides rigorous correctness and unconditional security proofs for both protocols and calculates the maximum tolerable error rate under the depolarizing channel assumption. The results offer practical guidance for the design of efficient SQKD protocols, highlighting two promising directions: optimizing the classical user’s random operations and exploiting underutilized quantum resources.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monogamy inequalities of entanglement of assistance in (2otimes 2otimes d) systems","authors":"Xue-Na Zhu,&nbsp;Gui Bao,&nbsp;Zhi-Xiang Jin,&nbsp;Shao-Ming Fei,&nbsp;Tao Li","doi":"10.1007/s11128-026-05288-w","DOIUrl":"10.1007/s11128-026-05288-w","url":null,"abstract":"<div><p>The monogamy relations characterize the distribution of quantum correlations among the multipartite quantum systems. We study the monogamy relations of the entanglement of assistance in <span>(2otimes 2otimes d)</span> systems. We present explicitly the relations satisfied by the concurrence, the tangle, and the concurrence of assistance, which can be used to derive rigorous monogamy relations. Detailed examples are given to illustrate our results.\u0000</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stable entanglement in (mathcal{P}mathcal{T}) symmetric non-Hermitian double Jaynes–Cummings model","authors":"Bao-gang Zhu,&nbsp;Ze-kai Tian,&nbsp;Yi-Lin Yang,&nbsp;Zhong-Xiao Man","doi":"10.1007/s11128-026-05285-z","DOIUrl":"10.1007/s11128-026-05285-z","url":null,"abstract":"<div><p>We study the <span>(mathcal{P}mathcal{T})</span> symmetry, dynamical evolution, entanglement and atomic population inversion of the non-Hermitian double Jaynes–Cummings model with <span>(mathcal{P}mathcal{T})</span> symmetry based on a given initial entangled state. We find that the presence of non-Hermitian terms divides the system into two distinct symmetry phases and leads to different behaviors. In the <span>(mathcal{P}mathcal{T})</span> symmetry phase, there exists Rabi oscillation caused by stable interactions between photons and atoms, and the entanglement exhibits entanglement sudden death (ESD) and entanglement sudden birth (ESB) phenomena. Meanwhile, the atomic population inversion changes periodically over time. As the coupling constant increases, the system transits from <span>(mathcal{P}mathcal{T})</span> symmetry phase to <span>(mathcal{P}mathcal{T})</span> symmetry breaking phase. In the symmetry breaking phase, the entanglement evolves to a nonzero value under certain circumstances, and the atomic population inversion shows similar feature. This study help us to understand the effect of symmetry on the interaction between photons and atoms in non-Hermitian system.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spin quantum computing, spin quantum cognition","authors":"Betony Adams,&nbsp;Francesco Petruccione","doi":"10.1007/s11128-026-05286-y","DOIUrl":"10.1007/s11128-026-05286-y","url":null,"abstract":"<div><p>Over two decades ago, Bruce Kane proposed that spin-half phosphorus nuclei embedded in a spin-zero silicon substrate could serve as a viable platform for spin-based quantum computing. These nuclear spins exhibit remarkably long single-spin coherence times, making them ideal candidates for qubits. Despite this advantage, practical realisation of spin quantum computing remains a challenge. More recently, physicist Matthew Fisher proposed a hypothesis linking nuclear spin dynamics, specifically those of phosphorus nuclei within the spin-zero matrix of calcium phosphate molecules, to neural activation and, potentially, cognition. The theory has generated both interest and scepticism, with some fundamental questions remaining. We review this intersection of quantum computing and quantum biology by outlining the similarities between these models of computing and cognition. We then address some of the open questions and the lessons that might be learned in each context. In doing so, we highlight a promising bidirectional exchange: not only might quantum computing offer tools for understanding quantum biology, but biological models may also inspire novel strategies for quantum information processing.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11128-026-05286-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multipolar and nonlocal effects in plasmon-mediated entanglement generation","authors":"Luke C. Ugwuoke,&nbsp;Tjaart P. J. Krüger,&nbsp;Mark S. Tame","doi":"10.1007/s11128-026-05281-3","DOIUrl":"10.1007/s11128-026-05281-3","url":null,"abstract":"<div><p>The generation of quantum entanglement is important for a wide range of quantum technology protocols. In nanophotonics, a promising platform for quantum technologies, entanglement generation via plasmon-mediated coupling in quantum dot qubits is often modeled within the dipole limit, where only dipolar plasmons of the mediating nanoparticle are considered, and the local response approximation, where nonlocal corrections are ignored. However, multipolar effects manifest strongly at coupling distances less than the nanoparticle size, while nonlocal optical effects stem from a size-induced dielectric response. We investigated these two important effects in the generation of two-qubit entanglement mediated by plasmonic coupling. A cavity quantum electrodynamic approach is employed, where the induced plasmonic effects lead to modified transition rates in the dynamics of the coupled quantum dot qubits. We find that multipolar modes and size-dependent damping lead to entanglement decay at small coupling distances and limit mediated entanglement with certain particle sizes. We discuss potential implications of multipolar modes in entanglement-based quantum sensing.</p></div>","PeriodicalId":746,"journal":{"name":"Quantum Information Processing","volume":"25 8","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11128-026-05281-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148466364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}