Quantum Science and Technology最新文献

Measurement schemes for quantum linear equation solvers

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-03-14 DOI: 10.1088/2058-9565/adbcd0

Andrew Patterson and Leigh Lapworth

{"title":"Measurement schemes for quantum linear equation solvers","authors":"Andrew Patterson and Leigh Lapworth","doi":"10.1088/2058-9565/adbcd0","DOIUrl":"https://doi.org/10.1088/2058-9565/adbcd0","url":null,"abstract":"Solving computational fluid dynamics (CFD) problems requires the inversion of a linear system of equations, which can be done using a quantum algorithm for matrix inversion (Gilyén et al 2019 Proc. 51st Annual ACM SIGACT Symp. on Theory of Computing 193–204). However, the number of shots required to measure the output of the system can be prohibitive and remove any advantage obtained by quantum computing. In this work we propose a scheme for measuring the output of a quantum singular value transform (QSVT) matrix inversion algorithm specifically for the CFD use case. We use a quantum signal processing based amplitude estimation algorithm (Rall and Fuller 2023 Quantum7 937) and show how it can be combined with the QSVT matrix inversion algorithm. We perform a detailed resource estimation of the amount of computational resources required for a single iteration of amplitude estimation, and compare the costs of amplitude estimation with the cost of not doing amplitude estimation and measuring the whole wavefunction. We also propose a measurement scheme to reduce the number of amplitudes measured in the CFD example by focussing on large amplitudes only. We simulate the whole CFD loop, finding that thus measuring only a small number of the total amplitudes in the output vector still results in an acceptable level of overall error.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"19 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143618785","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}

引用次数: 0

Dynamical invariant based shortcut to equilibration in open quantum systems

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-03-13 DOI: 10.1088/2058-9565/adbcce

Mohamed Boubakour, Shimpei Endo, Thomás Fogarty and Thomas Busch

引用次数: 0

Photon-mediated dipole–dipole interactions as a resource for quantum science and technology in cold atoms

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-03-10 DOI: 10.1088/2058-9565/adbb86

H H Jen

{"title":"Photon-mediated dipole–dipole interactions as a resource for quantum science and technology in cold atoms","authors":"H H Jen","doi":"10.1088/2058-9565/adbb86","DOIUrl":"https://doi.org/10.1088/2058-9565/adbb86","url":null,"abstract":"Photon-mediated dipole–dipole interactions arise from atom-light interactions, which are universal and prevalent in a wide range of open quantum systems. This pairwise and long-range spin-exchange interaction results from multiple light scattering among the atoms. A recent surge of interests and progresses in both experiments and theories promises this core mechanism of collective interactions as a resource to study quantum science and to envision next-generation applications in quantum technology. Here we summarize recent developments in both theories and experiments, where we introduce several central theoretical approaches and focus on cooperative light scattering from small sample of free-space atoms, an atom-waveguide coupled interface that hosts the waveguide QED, and topological quantum optical platforms. The aim of this review is to manifest the essential and distinct features of collective dynamics induced by resonant dipole–dipole interactions and to reveal unprecedented opportunities in enhancing the performance or offering new applications in light manipulations, quantum metrology, quantum computations, and light harvesting innovations.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"38 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143582687","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}

引用次数: 0

Effective field theories in broadband quantum optics: modeling phase modulation and two-photon loss from cascaded quadratic nonlinearities

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-02-28 DOI: 10.1088/2058-9565/adaedf

Chris Gustin, Ryotatsu Yanagimoto, Edwin Ng, Tatsuhiro Onodera and Hideo Mabuchi

{"title":"Effective field theories in broadband quantum optics: modeling phase modulation and two-photon loss from cascaded quadratic nonlinearities","authors":"Chris Gustin, Ryotatsu Yanagimoto, Edwin Ng, Tatsuhiro Onodera and Hideo Mabuchi","doi":"10.1088/2058-9565/adaedf","DOIUrl":"https://doi.org/10.1088/2058-9565/adaedf","url":null,"abstract":"In broadband quantum optical systems, nonlinear interactions among a large number of frequency components induce complex dynamics that may defy heuristic analysis. In this work we introduce a perturbative framework for factoring out reservoir degrees of freedom and establishing a concise effective model (effective field theory) for the remaining system. Our approach combines approximate diagonalization of judiciously partitioned subsystems with master equation techniques. We consider cascaded optical (quadratic) nonlinearities as an example and show that the dynamics can be construed (to leading order) as self-phase modulations of dressed fundamental modes plus cross-phase modulations of dressed fundamental and second-harmonic modes. We then formally eliminate the second-harmonic degrees of freedom and identify emergent features of the fundamental wave dynamics, such as two-photon loss channels, and examine conditions for accuracy of the reduced model in dispersive and dissipative parameter regimes. Our results highlight the utility of system-reservoir methods for deriving accurate, intuitive reduced models for complex dynamics in broadband nonlinear quantum photonics, and may help guide quantum technological proposals in emerging systems where quantum effects become significant at the single-photon level.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"27 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143517945","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}

引用次数: 0

Quantum-centric computation of molecular excited states with extended sample-based quantum diagonalization

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-02-27 DOI: 10.1088/2058-9565/adb781

Stefano Barison, Javier Robledo Moreno and Mario Motta

{"title":"Quantum-centric computation of molecular excited states with extended sample-based quantum diagonalization","authors":"Stefano Barison, Javier Robledo Moreno and Mario Motta","doi":"10.1088/2058-9565/adb781","DOIUrl":"https://doi.org/10.1088/2058-9565/adb781","url":null,"abstract":"The simulation of molecular electronic structure is an important application of quantum devices. Recently, it has been shown that quantum devices can be effectively combined with classical supercomputing centers in the context of the sample-based quantum diagonalization (SQD) algorithm. This allowed the largest electronic structure quantum simulation to date (77 qubits) and opened near-term devices to practical use cases in chemistry toward the hundred-qubit mark. However, the description of many important physical and chemical properties of those systems, such as photo-absorption/-emission, requires a treatment that goes beyond the ground state alone. In this work, we extend the SQD algorithm to determine low-lying molecular excited states. The extended-SQD method improves over the original SQD method in accuracy, at the cost of an additional computational step. It also improves over quantum subspace expansion based on single and double electronic excitations, a widespread approach to excited states on pre-fault-tolerant quantum devices, in both accuracy and efficiency. We employ the extended SQD method to compute the first singlet (S1) and triplet (T1) excited states of the nitrogen molecule with a correlation-consistent basis set, and the ground- and excited-state properties of the [2Fe-2S] cluster.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"21 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143506813","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}

引用次数: 0

A Gigahertz configurable silicon photonic integrated circuit nonlinear interferometer

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-02-21 DOI: 10.1088/2058-9565/adb176

Jonathan Frazer, Takafumi Ono and Jonathan C F Matthews

引用次数: 0

Non-iterative disentangled unitary coupled-cluster based on lie-algebraic structure

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-02-21 DOI: 10.1088/2058-9565/adb3c5

Mohammad Haidar, Olivier Adjoua, Siwar Badreddine, Alberto Peruzzo and Jean-Philip Piquemal

{"title":"Non-iterative disentangled unitary coupled-cluster based on lie-algebraic structure","authors":"Mohammad Haidar, Olivier Adjoua, Siwar Badreddine, Alberto Peruzzo and Jean-Philip Piquemal","doi":"10.1088/2058-9565/adb3c5","DOIUrl":"https://doi.org/10.1088/2058-9565/adb3c5","url":null,"abstract":"Due to their non-iterative nature, fixed unitary coupled cluster (UCC) ansätze are attractive for performing quantum chemistry variational quantum eigensolver (VQE) computations as they avoid pre-circuit measurements on a quantum computer. However, achieving chemical accuracy for strongly correlated systems with UCC requires further inclusion of higher-order fermionic excitations beyond triples increasing circuit depth. We introduce k-non-iterative disentangled unitary coupled cluster (NI-DUCC), a fixed and non-iterative disentangled UCC compact ansatz, based on specific ‘k’ sets of ‘qubit’ excitations, eliminating the needs for fermionic-type excitations. These elements scale linearly ( ) by leveraging Lie algebraic structures, with n being the number of qubits. The key excitations are screened through specific selection criteria, including the enforcement of all symmetries, to ensure the construction of a robust set of generators. NI-DUCC employs ‘k’ products of the exponential of - anti-Hermitian Pauli operators, where each single Pauli string has a length p. This results in a fewer two-qubit CNOT gates circuit scaling, , suitable for hardware implementations. Tested on LiH, H6 and BeH2, NI-DUCC-VQE achieves both chemical accuracy and rapid convergence even for molecules deviating significantly from equilibrium. It is hardware-efficient, reaching the exact full configuration interaction energy solution at specific layers, while reducing significantly the VQE optimization steps. NI-DUCC-VQE effectively addresses the gradient measurement bottleneck of ADAPT-VQE-like iterative algorithms, yet the classical computational cost of constructing the set of excitations increases exponentially with the number of qubits. We provide a first implementation for constructing the generators’ set, able to handle up to 20 qubits and discuss the efficiency perspectives.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"22 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143462832","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}

引用次数: 0

High-rate continuous-variable measurement device-independent quantum key distribution with finite-size security

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-02-21 DOI: 10.1088/2058-9565/adb2be

Adnan A E Hajomer, Ulrik L Andersen and Tobias Gehring

{"title":"High-rate continuous-variable measurement device-independent quantum key distribution with finite-size security","authors":"Adnan A E Hajomer, Ulrik L Andersen and Tobias Gehring","doi":"10.1088/2058-9565/adb2be","DOIUrl":"https://doi.org/10.1088/2058-9565/adb2be","url":null,"abstract":"Building scalable and secure quantum networks requires advanced quantum key distribution (QKD) protocols that support multi-user connectivity. Continuous-variable (CV) measurement-device-independent (MDI) QKD, which eliminates all detector side-channel attacks, is a promising candidate for creating various quantum network topologies-such as quantum access networks and star-type topologies-using standard technology and providing high secure key rates. However, its security has so far only been experimentally demonstrated in asymptotic regimes with limited secret key rates and complex experimental setups, limiting its practical applications. Here, we report an experimental validation of a CV MDI-QKD system, achieving a secure key rate of 2.6 Mbit s−1 against collective attacks in the finite-size regime over a 10 km fiber link. This is achieved using a new system design, incorporating a locally generated local oscillator, a new relay structure, a real-time phase locking system, and a well-designed digital-signal-processing pipeline for quantum state preparation and CV Bell measurements at a symbol rate of 20 MBaud. Our results set a new benchmark for secure key exchange and open the possibility of establishing high-performance CV MDI-QKD networks, paving the way toward a scalable quantum network.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"18 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143462824","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}

引用次数: 0

Quantum coding with finite thermodynamic resources

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-02-19 DOI: 10.1088/2058-9565/adb0e9

Jake Xuereb, Tiago Debarba, Marcus Huber and Paul Erker

{"title":"Quantum coding with finite thermodynamic resources","authors":"Jake Xuereb, Tiago Debarba, Marcus Huber and Paul Erker","doi":"10.1088/2058-9565/adb0e9","DOIUrl":"https://doi.org/10.1088/2058-9565/adb0e9","url":null,"abstract":"Quantum direct coding or Schumacher compression generalised the ideas of Shannon theory, gave an operational meaning to the von Neumann entropy and established the term qubit. But remembering that information processing is carried out by physical processes prompts one to wonder what thermodynamic resources are required to compress quantum information and how they constrain one’s ability to perform this task. That is, if Alice and Bob only have access to thermal quantum states and clocks with finite accuracy, how well can they measure, encode and decode pure quantum state messages? In this work we examine these questions by modeling Alice’s typical measurement as a unitary involving a measurement probe, investigating imperfect timekeeping on encoding and decoding and considering the role of temperature in Bob’s appended qubits. In doing so, we derive fidelity bounds for this protocol involving the correlations Alice can form with their measurement probe, the variance of the clock’s ticks and the temperature of Bob’s qubits. Finally, we give an insight into the entropy produced by these two agents throughout the compression protocol by relating the resources they use to a quantum thermodynamic cooling protocol.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"15 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443274","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}

引用次数: 0

Finding quantum codes via Riemannian optimization

IF 6.7 2区物理与天体物理

Quantum Science and Technology Pub Date : 2025-02-18 DOI: 10.1088/2058-9565/adb3c6

Miguel Casanova, Kentaro Ohki and Francesco Ticozzi

{"title":"Finding quantum codes via Riemannian optimization","authors":"Miguel Casanova, Kentaro Ohki and Francesco Ticozzi","doi":"10.1088/2058-9565/adb3c6","DOIUrl":"https://doi.org/10.1088/2058-9565/adb3c6","url":null,"abstract":"We propose a novel optimization scheme designed to find optimally correctable subspace codes for a known quantum noise channel. To each candidate subspace code we first associate a universal recovery map, as if the code was perfectly correctable, and aim to maximize a performance functional that combines a modified channel fidelity with a tuneable regularization term that promotes simpler codes. With this choice optimization is performed only over the set of codes, and not over the set of recovery operators. The set of codes of fixed dimension is parametrized as a complex-valued Stiefel manifold: the resulting non-convex optimization problem is then solved by gradient-based local algorithms. When perfectly correctable codes cannot be found, a second optimization routine is run on the recovery Kraus map, also parametrized in a suitable Stiefel manifold via Stinespring representation. To test the approach, correctable codes are sought in different scenarios and compared to existing ones: three qubits subjected to bit-flip errors (single and correlated), four qubits undergoing local amplitude damping and five qubits subjected to local depolarizing channels. Approximate codes are found and tested for the previous examples as well pure non-Markovian dephasing noise acting on a spin, induced by a spin bath, and the noise of the first three qubits of IBM’s ibm_kyoto quantum computer. The fidelity results are competitive with existing iterative optimization algorithms, with respect to which we maintain a strong computational advantage, while obtaining simpler codes.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"3 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143435048","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}

引用次数: 0