Quantum Science and Technology最新文献

{"title":"Exploring semiconductor qubits: simulation of a four quantum dot silicon device","authors":"Giovanni Pedicini, Antonio Tudisco, Mario Cignoni, Mariagrazia Graziano, Gianluca Piccinini and Fabrizio Riente","doi":"10.1088/2058-9565/adf6d1","DOIUrl":"https://doi.org/10.1088/2058-9565/adf6d1","url":null,"abstract":"Quantum computing represents a revolutionary computational paradigm with the potential to overcome the limitations of classical computers. Among the various approaches under investigation, semiconductor-based solutions stand out as promising candidates for qubit implementation. This work explores a four-quantum dot SiGe heterostructure. The above structure has been analyzed using the low-level finite element method-based simulator quantum technology computer-aided design (QTCAD) to derive essential physical parameters critical for implementing electron spin qubits. Even though QTCAD may not be as accurate as real experiments, it nonetheless provides important insights into the device behavior. The aim is to use these simulations to effectively analyze the device’s response to changes in structural parameters and determine whether it is feasible for real-world applications. As a result, changes to the structure can be made by simply modifying the simulation code, avoiding the need for repetitive and expensive lithographic processes. Notably, this is the first time a four-quantum-dot system has been analyzed using QTCAD. Specifically, the study involves solving the non-linear Poisson equation as well as single and multi particle Schrödinger equations. Additionally, a transport analysis is performed, yielding Coulomb peaks, Coulomb diamonds, and charge stability diagrams. Finally, an approximation of the tunneling coefficient and the exchange interaction energy between the different dot pairs is computed. The results provide a foundation for the design of advanced logic circuits able to execute multiple quantum logic gates. By leveraging the precise control over quantum dot configuration, it becomes possible to customize the interactions between quantum states for specific computational purposes. This approach enables the realization of complex architectures where individual quantum dots act as qubits or nodes in a quantum network. The ability to tune gate voltages and control inter-dot couplings allows for the implementation of complex quantum logic gates.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"5 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144819935","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":"Squeezing generation crossing a mean-field critical point: work statistics, irreversibility, and critical fingerprints","authors":"Fernando J Gómez-Ruiz, Stefano Gherardini and Ricardo Puebla","doi":"10.1088/2058-9565/adf5de","DOIUrl":"https://doi.org/10.1088/2058-9565/adf5de","url":null,"abstract":"Understanding the dynamical consequences of quantum phase transitions on thermodynamical quantities, such as work statistics and entropy production, is one of the most intriguing aspect of quantum many-body systems, pinpointing the emergence of irreversibility to critical features. In this work, we investigate the critical fingerprints appearing in these key thermodynamical quantities for a mean-field critical system undergoing a finite-time cycle, starting from a thermal state at a generic inverse temperature. In contrast to non-zero dimensional many-body systems, the presence of a mean-field critical point in a finite-time cycle leads to constant irreversible work even in the limit of infinitely slow driving. This links with the fact that a slow finite-time cycle results in a constant amount of squeezing, which enables us to derive analytical expressions for the work statistics and irreversible entropy, depending solely on the mean-field critical exponents and the functional form of the control parameter near the critical point. We find that the probability of observing negative work values, corresponding to negative irreversible entropy, is inversely proportional to the time the system remains near to the critical point, and this trend becomes less pronounced the lower the temperature of the initial thermal state. Finally, we determine the irreversibility traits under squeezing generation at zero-temperature using the relative entropy of coherence.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"38 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144819320","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":"Quasiprobability distributions with weak measurements","authors":"G Bizzarri, S Gherardini, M Manrique, F Bruni, I Gianani and M Barbieri","doi":"10.1088/2058-9565/adf573","DOIUrl":"https://doi.org/10.1088/2058-9565/adf573","url":null,"abstract":"We discuss and experimentally demonstrate the role of quantum coherence in a sequence of two measurements collected at different times using weak measurements. For this purpose, we have realized a weak-sequential measurement protocol with photonic qubits, where the first measurement is carried out as a positive operator-valued measure, whereas the second one is a projective operation. We determine the quasiprobability distributions associated to this procedure using both the commensurate and the Margenau-Hill quasiprobabilities. By tuning the weak measurements, we obtain a quasidistribution that may or may not exhibit negative parts, depending on the suitability of a contextual model for describing the experiment. Our results show how quasidistributions may find application in inspecting quantum monitoring, when part of the initial quantum coherence needs to be preserved.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"32 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144796889","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":"Enhancing the energy gap of random graph problems via XX-catalysts in quantum annealing","authors":"Luca A Nutricati, Roopayan Ghosh, Natasha Feinstein, Sougato Bose and P A Warburton","doi":"10.1088/2058-9565/adf2d5","DOIUrl":"https://doi.org/10.1088/2058-9565/adf2d5","url":null,"abstract":"One of the main challenges in solving combinatorial optimisation problems with quantum annealers is the emergence of extremely small energy gaps between the ground state and the first excited state of the annealing Hamiltonian. These small gaps may be symptoms of an underlying first-order phase transition, which, according to the adiabatic theorem, can significantly extend the required anneal time, making practical implementation effectively infeasible. In this paper we demonstrate that attaching an XX-catalyst on all the edges of a graph upon which a MWIS (Maximum Weighted Independent Set) problem is defined, significantly enhances the minimum energy gap. Remarkably, our analysis shows that the smaller the energy gap, the more effective the catalyst is in opening it. This result is based on a detailed statistical analysis performed on a large number of randomly generated MWIS problem instances on both Erdõs–Rényi and Barabáasi–Albert graphs. We perform the analysis using both stoquastic and non-stoquastic catalysts.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"31 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144796786","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":"Robust entanglement buffers based on SWAP interactions","authors":"Ye-Chao Liu, Otfried Gühne and Stefan Nimmrichter","doi":"10.1088/2058-9565/adf2d7","DOIUrl":"https://doi.org/10.1088/2058-9565/adf2d7","url":null,"abstract":"Quantum entanglement is the essential resource for quantum communication and distributed information processing in a quantum network. However, the remote generation over a network suffers from inevitable transmission loss and other technical difficulties. This paper introduces the concept of entanglement buffers as a potential primitive for preparing long-distance entanglement. We investigate the filling of entanglement buffers with either one Bell state or a stream of Bell states via SWAP interactions. We illustrate their resilience to imperfect interactions, noise, and losses, making the buffers suitable for a realistic quantum network scenario. Additionally, larger entanglement buffers can always enhance these benefits.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"36 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144796914","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":"Leveraging commuting groups for an efficient variational Hamiltonian ansatz","authors":"Abhinav Anand and Kenneth R Brown","doi":"10.1088/2058-9565/adf507","DOIUrl":"https://doi.org/10.1088/2058-9565/adf507","url":null,"abstract":"Efficiently calculating the low-lying eigenvalues of Hamiltonians, written as sums of Pauli operators, is a fundamental challenge in quantum computing. While various methods have been proposed to reduce the complexity of quantum circuits for this task, there remains room for further improvement. In this article, we introduce a new circuit design using commuting groups within the Hamiltonian to further reduce the circuit complexity of Hamiltonian-based quantum circuits. Our approach involves partitioning the Pauli operators into mutually commuting clusters and finding Clifford unitaries that diagonalize each cluster. We then design an ansatz that uses these Clifford unitaries for efficient switching between the clusters, complemented by a layer of parameterized single qubit rotations for each individual cluster. By conducting numerical simulations, we demonstrate the effectiveness of our method in accurately determining the ground state energy of different quantum chemistry Hamiltonians. Our results highlight the applicability and potential of our approach for designing problem-inspired ansatz for various quantum computing applications.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"10 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144796943","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":"Integration of a high-fidelity model of quantum sensors with a map-matching filter for quantum-enhanced navigation","authors":"Samuel Lellouch and Michael Holynski","doi":"10.1088/2058-9565/adf2d9","DOIUrl":"https://doi.org/10.1088/2058-9565/adf2d9","url":null,"abstract":"Harnessing the potential of quantum sensors to assist in navigation requires enabling their operation in complex, dynamic environments and integrating them within existing navigation systems. While cross-couplings from platform dynamics generally degrade quantum measurements in a complex manner, navigation filters would need to be designed to handle such complex quantum sensor data. In this work, we report on the realization of a high-fidelity model of an atom-interferometry-based gravity gradiometer and demonstrate its integration with a map-matching navigation filter. Relying on the ability of our model to simulate the sensor behaviour across various dynamic platform environments, we show that aiding navigation via map matching using quantum gravity gradiometry results in stable trajectories, and highlight the importance of non-Gaussian errors arising from platform dynamics as a key challenge to map-matching navigation. We derive requirements for mitigating these errors, such as maintaining sensor tilt below 3.3∘, to inform future sensor development priorities. This work demonstrates the value of an end-to-end approach that could support future optimization of the overall navigation system. Beyond navigation, our atom interferometer modelling framework could be relevant to current research and innovation endeavours with quantum gravimeters, gradiometers and inertial sensors.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144786593","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":"Readout of strongly coupled NV center-pair spin states with deep neural networks","authors":"Matthew Joliffe, Vadim Vorobyov and Jörg Wrachtrup","doi":"10.1088/2058-9565/adf2d6","DOIUrl":"https://doi.org/10.1088/2058-9565/adf2d6","url":null,"abstract":"Optically addressable electron spin clusters are of interest for quantum computation, simulation and sensing. However, with interaction length scales of a few tens of nanometers in the strong coupling regime, they are unresolved in conventional confocal microscopy, making individual readout problematic. Here we show that when using a single shot readout technique, collective states of the combined register space become accessible. By using spin to charge conversion of the defects we draw the connection between the intricate photon count statistics with spin state readout using deep neural networks. This approach is particularly versatile with further scaling the number of constituent spins in a cluster due to complexity of the analytical treatment. We perform a proof of concept measurement of the correlated classical signal, paving the way for using our technique in realistic applications.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"29 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144778325","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":"Scalable chip-based 3D ion traps","authors":"Elena Jordan, Malte Brinkmann, Alexandre Didier, Erik Jansson, Martin Steinel, Nils Huntemann, Hu Shao, Hendrik Siebeneich, Christof Wunderlich, Michael Johanning and Tanja E Mehlstäubler","doi":"10.1088/2058-9565/adf2db","DOIUrl":"https://doi.org/10.1088/2058-9565/adf2db","url":null,"abstract":"Ion traps are used for a wide range of applications from metrology to quantum simulations and quantum information processing. Microfabricated chip-based 3D ion traps are scalable to store many ions for the realization of a large number of qubits, provide deep trapping potentials compared to surface traps, and very good shielding from external electric fields. In this work, we give an overview of our recent developments on chip-based 3D ion traps. Different types of chip materials, the integration of electronic filter components on-chip and compact electrical connections in vacuum are discussed. Further, based on finite element method simulations, we discuss how integrating micro-optics in 3D ion traps is possible without disturbing the trapped ions.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"15 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144778326","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":"Towards experimental demonstration of quantum position verification using single photons","authors":"Kirsten Kanneworff, Mio Poortvliet, Dirk Bouwmeester, Rene Allerstorfer, Philip Verduyn Lunel, Florian Speelman, Harry Buhrman, Petr Steindl and Wolfgang Löffler","doi":"10.1088/2058-9565/adf2da","DOIUrl":"https://doi.org/10.1088/2058-9565/adf2da","url":null,"abstract":"The geographical position can be a good credential for authentication of a party. This is the basis of position-based cryptography—but classically this cannot be done securely without physical exchange of a private key. Recently it has been shown that by combining quantum mechanics with the speed-of-light limit of special relativity, this might be possible: quantum position verification (QPV). Here we demonstrate experimentally a protocol that uses two-photon Hong–Ou–Mandel interference at a beamsplitter, which, in combination with two additional beam splitters and four detectors is rendering the protocol resilient to loss. With this, we are able to show first results towards an experimental demonstration of QPV.","PeriodicalId":20821,"journal":{"name":"Quantum Science and Technology","volume":"117 1","pages":""},"PeriodicalIF":6.7,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144756481","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}