Quantum Science and Technology最新文献

{"title":"AI and quantum computing ethics- same but different? Towards a new sub-field of computing ethics","authors":"R Coates, D Douglas and M Per","doi":"10.1088/2058-9565/add9c2","DOIUrl":"https://doi.org/10.1088/2058-9565/add9c2","url":null,"abstract":"As quantum computing development advances closer toward achieving fault-tolerant error-corrected realisation, debates on applications, impacts, risks, and benefits of quantum computing are timely and due. While there is awareness of the potential power and complexity of quantum computers, there has been relatively little attention on the social impacts and ethical implications of this technology. In grappling with the social impacts of quantum computing, some stakeholders have turned to applied ethics, specifically (classical) computer and Artificial Intelligence (AI) ethics, for guidance. While computer and AI ethics are useful starting points for evaluating the ethical issues posed by quantum computing, uncritically applying existing sets of ethical principles risks overlooking how quantum computing differs from these technologies. We argue that borrowing of ethical principles and guidelines from AI and computing is inappropriate for several reasons: (1) quantum computing, classical computing, and AI are different technologies with significant material differences; (2) unlike AI and classical computers which have become established, quantum computing is an emerging technology, which has implications on the levels of accessibility and immediate impact in society; and (3) there are significant differences in the way AI and quantum computing have been developed and by whom. We also briefly summarise some of the unique risks and societ al impacts posed by quantum computing. We posit that these reasons support the argument for a new sub-field of quantum computing ethics, which would allow a relevant scholarship to develop and provide guidance as quantum computing technology continues to mature.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"57 1","pages":"035030"},"PeriodicalIF":6.7,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144145710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Selective and noise-resilient wave estimation with quantum sensor networks","authors":"Arne Hamann, Paul Aigner, Wolfgang Dür and Pavel Sekatski","doi":"10.1088/2058-9565/add61b","DOIUrl":"https://doi.org/10.1088/2058-9565/add61b","url":null,"abstract":"We consider the selective sensing of planar waves in the presence of noise. We present different methods to control the sensitivity of a quantum sensor network, which allow one to decouple it from arbitrarily selected waves while retaining sensitivity to the signal. Comparing these methods with classical (non-entangled) sensor networks we demonstrate two advantages. First, entanglement increases precision by enabling the Heisenberg scaling. Second, entanglement enables the elimination of correlated noise processes corresponding to waves with different propagation directions, by exploiting decoherence-free subspaces. We then provide a theoretical and numerical analysis of the advantage offered by entangled quantum sensor networks, which is not specific to waves and can be of general interest. We demonstrate an exponential advantage in the regime where the number of sensor locations is comparable to the number of noise sources. Finally, we outline a generalization to other waveforms, e.g. spherical harmonics and general time-dependent fields.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"135 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"A flexible SoC for quantum key distribution post-processing based on RISC-V processor","authors":"Xinyi Wu, Lianye Liao, Xiaodong Fan, Ye Chen, Jinquan Huang, Minjie Liu, Zhiyu Tian, Tonglin Mu, Junran Guo, Bo Liu and Shihai Sun","doi":"10.1088/2058-9565/add801","DOIUrl":"https://doi.org/10.1088/2058-9565/add801","url":null,"abstract":"In the domain of quantum-secure communications, post-processing emerges as a critical mechanism to ensure the security and integrity of the generated keys generated by quantum key distribution (QKD). However, existing post-processing frameworks often lack universality, being highly tailored to single-algorithm implementations and frequently neglecting key aspects such as system scalability and integration. To address these limitations, we present a novel system-on-chip (SoC) architecture for QKD post-processing, built around a co-designed framework featuring a RISC-V soft-core processor. This architecture incorporates core functionalities essential to QKD post-processing, including privacy amplification, information reconciliation, and high-speed communication interfaces. By leveraging the flexibility of the open-source RISC-V instruction set, the system achieves enhanced adaptability and energy efficiency. Additionally, a separated-bus architecture is employed, decoupling data and instruction buses to optimize data transfer efficiency and overall system performance, paving the way for scalable and high-throughput quantum communication systems. The system is deployed on the Xilinx Kintex Ultrascale series development board. At the Bob side, with a frame length of 16 384, the information reconciliation module and the privacy amplification module achieves throughputs of 29.73 Mbps and 131.07 Mbps, respectively.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"153 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Universal programmable waveguide arrays","authors":"Akram Youssry and Alberto Peruzzo","doi":"10.1088/2058-9565/add802","DOIUrl":"https://doi.org/10.1088/2058-9565/add802","url":null,"abstract":"Implementing arbitrary unitary transformations is crucial for applications in quantum computing, signal processing, and machine learning. Unitaries govern quantum state evolution, enabling reversible transformations critical in quantum tasks like cryptography and simulation and playing key roles in classical domains such as dimensionality reduction and signal compression. Integrated optical waveguide arrays have emerged as a promising platform for these transformations, offering scalability for both quantum and classical systems. However, scalable and efficient methods for implementing arbitrary unitaries remain challenging. Here, we present a theoretical framework for realizing arbitrary unitary matrices through programmable waveguide arrays (PWAs). We provide a mathematical proof demonstrating that cascaded PWAs can implement any unitary matrix within practical constraints, along with a numerical optimization method for customized PWA designs. Our results establish PWAs as a universal and scalable architecture for quantum photonic computing, effectively bridging quantum and classical applications, and positioning PWAs as an enabling technology for advancements in quantum simulation, machine learning, secure communication, and signal processing.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"42 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Motion-insensitive time-optimal control of optical qubits","authors":"Léo Van Damme, Zhao Zhang, Amit Devra, Steffen J Glaser and Andrea Alberti","doi":"10.1088/2058-9565/add61c","DOIUrl":"https://doi.org/10.1088/2058-9565/add61c","url":null,"abstract":"We derive new, fundamental insights into the dynamics of an optical qubit, revealing how this is influenced by the motion of the trapped particle. Leveraging these new insights, we show that photon-recoil heating can be suppressed at relatively high Rabi frequencies by modulating the phase of the driving laser field in time. This technique enables single-qubit gates that are up to 20 times faster than current state-of-the-art approaches while maintaining the same fidelity. Remarkably, even when photon recoil is eliminated (i.e. when occupation of Fock states is preserved), we find that the gate infidelity does not vanish, but is rather limited by a fundamental mechanism, which we identify as thermal motion-induced entanglement. To overcome this limitation and the effect of recoil, we derive motion-insensitive control pulses that enable the execution of fast, very high-fidelity gates with optical qubits.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"38 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144104584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Rapid charging of a two-qubit quantum battery by transverse field amplitude and phase control","authors":"Vasileios Evangelakos, Emmanuel Paspalakis and Dionisis Stefanatos","doi":"10.1088/2058-9565/add207","DOIUrl":"https://doi.org/10.1088/2058-9565/add207","url":null,"abstract":"We consider a quantum battery (QB) composed of a pair of qubits coupled with an Ising interaction in the usual NMR framework, where the longitudinal applied field is constant and the time-dependent variables controlling the system are the amplitude and phase of the transverse field, and use optimal control to derive fast charging protocols. We study both the cases where the Ising coupling is weaker and stronger than the longitudinal field. In the first case, where the lowest-energy state of the system is the spin-down state, the optimal charging protocol stipulates the transverse field amplitude to be constant and equal to its maximum allowed value, while the minimum time for full charging of the battery tends to zero as this maximum bound increases. In the second case, where the lowest-energy state is a maximally entangled Bell state, the optimal charging protocol includes a time interval where the transverse field amplitude is zero and its phase is immaterial, corresponding to singular control. In this case, the QB can be charged with higher levels of stored energy, while the minimum time for full charging tends to a nonzero limit proportional to the inverse Ising interaction, as the maximum bound of the control amplitude increases. We analyze intuitively and quantitatively the distinct behavior of the two cases and additionally use the dynamical Lie algebra of the system to elucidate the presence of a singular arc in the optimal pulse-sequence in the second case. The discovered interplay between the QB parameters, the stored energy and the minimum time for full charging, provides great flexibility for optimizing the performance of the device according to the operating constraints. The valuable insights gained regarding the design of QBs is expected to find immediate applications in modern quantum science and technology, while we aim to extend the proposed methods to larger spin chains.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"33 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144097663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Amplification, mitigation and energy storage via constrained thermalization","authors":"Midhun Krishna, Harshank Shrotriya, Leong-Chuan Kwek, Varun Narasimhachar and Sai Vinjanampathy","doi":"10.1088/2058-9565/add55c","DOIUrl":"https://doi.org/10.1088/2058-9565/add55c","url":null,"abstract":"Amplification (mitigation) is the increase (decrease) in the change of thermodynamic quantities when an initial thermal state is thermalized to a different temperature in the presence of constraints, studied thus far only for permutationally invariant baths. In this manuscript, we generalize amplification and mitigation to accommodate generic strong symmetries of open quantum systems and connect the phenomenon to Landauer’s erasure. We exemplify our general theory with a new bath-induced battery charging protocol that overcomes the passivity of KMS-preserving transitions.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"60 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144097669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Efficient estimation and sequential optimization of cost functions in variational quantum algorithms","authors":"Muhammad Umer, Eleftherios Mastorakis and Dimitris G Angelakis","doi":"10.1088/2058-9565/add55e","DOIUrl":"https://doi.org/10.1088/2058-9565/add55e","url":null,"abstract":"Classical optimization is a cornerstone of the success of variational quantum algorithms, which often require determining the derivatives of the cost function relative to variational parameters. The computation of the cost function and its derivatives, coupled with their effective utilization, facilitates faster convergence by enabling smooth navigation through complex landscapes, ensuring the algorithm’s success in addressing challenging variational problems. In this work, we introduce a novel problem-tailored optimization methodology that conceptualizes the parameterized quantum circuit as a weighted sum of distinct unitary operators, enabling the cost function to be expressed as a sum of multiple terms. This representation facilitates the efficient evaluation of nonlocal characteristics of cost functions, as well as their arbitrary derivatives. The optimization protocol then utilizes the nonlocal information on the cost function to facilitate a more efficient navigation process, ultimately enhancing the performance in the pursuit of optimal solutions. We utilize this methodology for two distinct cost functions. The first is the squared residual of the variational state relative to a target state, which is subsequently employed to examine the nonlinear dynamics of fluid configurations governed by the one-dimensional Burgers’ equation. The second cost function is the expectation value of an observable, which is later utilized to approximate the ground state of the nonlinear Schrödinger equation. Our findings reveal substantial enhancements in convergence speed and accuracy relative to traditional optimization methods, even within complex, high-dimensional landscapes. Our work contributes to the advancement of optimization strategies for variational quantum algorithms, establishing a robust framework for addressing a range of computationally intensive problems across numerous applications.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"35 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144088272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Unraveling quantum phase estimation: exploring the impact of multi-photon interference on the quantum Fisher information","authors":"A Ma, A G Magnoni, M A Larotonda and L T Knoll","doi":"10.1088/2058-9565/add04d","DOIUrl":"https://doi.org/10.1088/2058-9565/add04d","url":null,"abstract":"Quantum interference is known to become extinct with distinguishing information, as illustrated by the ubiquitous double-slit experiment or the two-photon Hong–Ou–Mandel effect. In the former case single particle interference is destroyed with which-path information while in the latter bunching interference tails-off as photons become distinguishable. It has been observed that when more than two particles are involved, these interference patterns are in general a non-monotonic function of the distinguishability. Here we perform a comprehensive characterization, both theoretically and experimentally, of four-photon interference by analyzing the corresponding correlation functions, contemplating several degrees of distinguishability across different parameters. This study provides all the necessary tools to quantify the impact of multi-photon interference on precision measurements of parameters such as phase, frequency, and time difference. We apply these insights to quantify the precision in the estimation of an interferometric phase in a two-port interferometer using a four-photon state. Our results reveal that, for certain phase values, partially distinguishable multi-photon states can achieve higher Fisher information values compared to the two-photon experiment. These findings highlight the potential of distinguishable multi-photon states for enhanced precision in quantum metrology and related applications.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"30 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"The travelling salesperson problem and the challenges of near-term quantum advantage","authors":"Kate A Smith-Miles, Holger H Hoos, Hao Wang, Thomas Bäck and Tobias J Osborne","doi":"10.1088/2058-9565/add61d","DOIUrl":"https://doi.org/10.1088/2058-9565/add61d","url":null,"abstract":"Over the last two decades, the travelling salesperson problem (TSP) has been cited as a benchmark problem to demonstrate the advantage of quantum computers over conventional computers. Its advantage is that it is a well-studied NP-hard optimisation problem that can be easily communicated to highlight the challenges of searching through an exponentially growing number of possible solutions to find the optimal solution. It is therefore a tempting problem to choose to explore quantum advantage. At what point, however, is a call made that quantum advantage is not likely, and efforts should be focused on other problems? This article challenges the continued use of the TSP as a benchmark for quantum optimisation methods—such as quantum annealing and gate-based quantum computing—that require the TSP to be formulated as a quadratic unconstrained binary optimisation (QUBO) problem. We offer explanations for why such quantum approaches are not well suited, nor competitive against state-of-the-art classical methods, for tackling the challenges of the TSP landscape, and we draw parallels with similar observations made almost four decades ago when QUBO-based neural networks proved to be uncompetitive for solving the TSP. After critically reviewing two decades of research effort to solve TSPs using QUBO-based quantum methods, we note a gradual shift in focus: from initial attempts to solve small sized TSPs with general-purpose QUBO-based quantum approaches, to growing evidence that competitiveness is only enhanced where TSP domain knowledge is integrated, via either modified formulations or hybridisation with TSP classical heuristics. We discuss the numerous challenges that must be overcome before QUBO-based quantum optimisers could ever be competitive with classical state-of-the-art TSP solvers. Acknowledging that there may be more promise for non-QUBO-based hybrid approaches, where quantum search accelerates components of conventional algorithms, we offer recommendations for how future studies should be conducted to compare fairly and rigorously any proposed quantum methods against state-of-the-art TSP solvers, or any classical optimisation method, when seeking to establish quantum advantage.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"14 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144066454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}