Pub Date : 2025-11-10DOI: 10.1038/s41534-025-01112-y
Simone Cavazzoni, Berihu Teklu, Matteo G. A. Paris
{"title":"Frequency estimation by frequency jumps","authors":"Simone Cavazzoni, Berihu Teklu, Matteo G. A. Paris","doi":"10.1038/s41534-025-01112-y","DOIUrl":"https://doi.org/10.1038/s41534-025-01112-y","url":null,"abstract":"","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"22 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145477984","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-07DOI: 10.1038/s41534-025-01111-z
Eugenio Caruccio, Diego Maragnano, Giovanni Rodari, Davide Picus, Giovanni Garberoglio, Daniele Binosi, Riccardo Albiero, Niki Di Giano, Francesco Ceccarelli, Giacomo Corrielli, Nicolò Spagnolo, Roberto Osellame, Maurizio Dapor, Marco Liscidini, Fabio Sciarrino
Reconstructing the state of a quantum system represents a pivotal task for quantum information applications. The standard approach based on quantum state tomography requires a number of measurements that scales exponentially with the number of qubits. Other methods have been proposed and tested to reduce the number of measurements, or to focus on specific properties of the output state rather than on its complete reconstruction. Here, we show experimentally the application of an approach, called threshold quantum state tomography, in an advanced hybrid photonic platform with states up to n = 4 qubits. This method does not require prior knowledge and selects only the informative projectors starting from the measurement of the density matrix diagonal. We demonstrate its effectiveness by showing that a consistent reduction in the number of measurements is obtained for relevant states, with only very limited loss of information. These results open perspective for its application in larger systems.
{"title":"Experimental verification of threshold quantum state tomography on a fully-reconfigurable photonic integrated circuit","authors":"Eugenio Caruccio, Diego Maragnano, Giovanni Rodari, Davide Picus, Giovanni Garberoglio, Daniele Binosi, Riccardo Albiero, Niki Di Giano, Francesco Ceccarelli, Giacomo Corrielli, Nicolò Spagnolo, Roberto Osellame, Maurizio Dapor, Marco Liscidini, Fabio Sciarrino","doi":"10.1038/s41534-025-01111-z","DOIUrl":"https://doi.org/10.1038/s41534-025-01111-z","url":null,"abstract":"Reconstructing the state of a quantum system represents a pivotal task for quantum information applications. The standard approach based on quantum state tomography requires a number of measurements that scales exponentially with the number of qubits. Other methods have been proposed and tested to reduce the number of measurements, or to focus on specific properties of the output state rather than on its complete reconstruction. Here, we show experimentally the application of an approach, called threshold quantum state tomography, in an advanced hybrid photonic platform with states up to <jats:italic>n</jats:italic> = 4 qubits. This method does not require prior knowledge and selects only the informative projectors starting from the measurement of the density matrix diagonal. We demonstrate its effectiveness by showing that a consistent reduction in the number of measurements is obtained for relevant states, with only very limited loss of information. These results open perspective for its application in larger systems.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"49 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145455636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-11-05DOI: 10.1038/s41534-025-01086-x
Pawel Blasiak, Marcin Markiewicz
{"title":"Identical particles as a genuine non-local resource","authors":"Pawel Blasiak, Marcin Markiewicz","doi":"10.1038/s41534-025-01086-x","DOIUrl":"https://doi.org/10.1038/s41534-025-01086-x","url":null,"abstract":"","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"27 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145440878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-10-27DOI: 10.1038/s41534-025-01069-y
Yipei Zhang, Philippe Lewalle, K. Birgitta Whaley
We generalize the projection–based quantum measurement–driven k –SAT algorithm of Benjamin, Zhao, and Fitzsimons 1 to arbitrary strength quantum measurements, including the limit of continuous monitoring. In doing so, we clarify that this algorithm is a particular case of the measurement–driven quantum control strategy elsewhere referred to as “Zeno dragging”. We argue that the algorithm is most efficient with finite time and measurement resources in the continuum limit, where measurements have an infinitesimal strength and duration. Moreover, for solvable k -SAT problems, the dynamics generated by the algorithm converge deterministically towards target dynamics in the long–time (Zeno) limit, implying that the algorithm can successfully operate autonomously via Lindblad dissipation, without detection. We subsequently study both the conditional and unconditional dynamics of the algorithm implemented via generalized measurements, quantifying the advantages of detection for heralding errors. These strategies are investigated first in a computationally–trivial 2-qubit 2-SAT problem to build intuition, and then we consider the scaling of the algorithm on 3-SAT problems encoded with 4–10 qubits. We numerically investigate the scaling of 3-SAT with respect to algorithmic runtime and find that the optimized time to solution scales with qubit number n as λn , where λ is slightly larger than $$sqrt{2}$$2 for unconditional dynamics and less than $$sqrt{2}$$2 for conditional dynamics. We assess the implications for using this analog measurement–driven approach to quantum computing in practice.
{"title":"Solving k–SAT problems with generalized quantum measurement","authors":"Yipei Zhang, Philippe Lewalle, K. Birgitta Whaley","doi":"10.1038/s41534-025-01069-y","DOIUrl":"https://doi.org/10.1038/s41534-025-01069-y","url":null,"abstract":"We generalize the projection–based quantum measurement–driven <jats:italic>k</jats:italic> –SAT algorithm of Benjamin, Zhao, and Fitzsimons <jats:sup>1</jats:sup> to arbitrary strength quantum measurements, including the limit of continuous monitoring. In doing so, we clarify that this algorithm is a particular case of the measurement–driven quantum control strategy elsewhere referred to as “Zeno dragging”. We argue that the algorithm is most efficient with finite time and measurement resources in the continuum limit, where measurements have an infinitesimal strength and duration. Moreover, for solvable <jats:italic>k</jats:italic> -SAT problems, the dynamics generated by the algorithm converge deterministically towards target dynamics in the long–time (Zeno) limit, implying that the algorithm can successfully operate autonomously via Lindblad dissipation, without detection. We subsequently study both the conditional and unconditional dynamics of the algorithm implemented via generalized measurements, quantifying the advantages of detection for heralding errors. These strategies are investigated first in a computationally–trivial 2-qubit 2-SAT problem to build intuition, and then we consider the scaling of the algorithm on 3-SAT problems encoded with 4–10 qubits. We numerically investigate the scaling of 3-SAT with respect to algorithmic runtime and find that the optimized time to solution scales with qubit number <jats:italic>n</jats:italic> as <jats:italic>λ</jats:italic> <jats:sup> <jats:italic>n</jats:italic> </jats:sup> , where <jats:italic>λ</jats:italic> is slightly larger than <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$sqrt{2}$$</jats:tex-math> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msqrt> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msqrt> </mml:math> </jats:alternatives> </jats:inline-formula> for unconditional dynamics and less than <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$sqrt{2}$$</jats:tex-math> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:msqrt> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msqrt> </mml:math> </jats:alternatives> </jats:inline-formula> for conditional dynamics. We assess the implications for using this analog measurement–driven approach to quantum computing in practice.","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"58 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145381785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-10-23DOI: 10.1038/s41534-025-01127-5
Giovanni Finco, Filippo Miserocchi, Andreas Maeder, Jost Kellner, Alessandra Sabatti, Robert J. Chapman, Rachel Grange
{"title":"Author Correction: Time-bin entangled Bell state generation and tomography on thin-film lithium niobite","authors":"Giovanni Finco, Filippo Miserocchi, Andreas Maeder, Jost Kellner, Alessandra Sabatti, Robert J. Chapman, Rachel Grange","doi":"10.1038/s41534-025-01127-5","DOIUrl":"https://doi.org/10.1038/s41534-025-01127-5","url":null,"abstract":"","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"16 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145382405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-10-22DOI: 10.1038/s41534-025-01107-9
Yohei Nishino, James W. Gardner, Yanbei Chen, Kentaro Somiya
{"title":"Teleportation-based speed meter for precision measurement","authors":"Yohei Nishino, James W. Gardner, Yanbei Chen, Kentaro Somiya","doi":"10.1038/s41534-025-01107-9","DOIUrl":"https://doi.org/10.1038/s41534-025-01107-9","url":null,"abstract":"","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"351 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145382406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Pub Date : 2025-10-21DOI: 10.1038/s41534-025-01115-9
Pratyush Anand, Ethan G. Arnault, Matthew E. Trusheim, Kurt Jacobs, Dirk R. Englund
{"title":"Microwave single-photon detection using a hybrid spin-optomechanical quantum interface","authors":"Pratyush Anand, Ethan G. Arnault, Matthew E. Trusheim, Kurt Jacobs, Dirk R. Englund","doi":"10.1038/s41534-025-01115-9","DOIUrl":"https://doi.org/10.1038/s41534-025-01115-9","url":null,"abstract":"","PeriodicalId":19212,"journal":{"name":"npj Quantum Information","volume":"71 1","pages":""},"PeriodicalIF":7.6,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145381789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
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