Bosonic cat qubits stabilized with a driven two-photon dissipation are systems with exponentially biased noise, opening the door to low-overhead, fault-tolerant and universal quantum computing. However, current gate proposals for such qubits induce substantial noise of the unprotected type, whose poor scaling with the relevant experimental parameters limits their practical use. In this work, we provide a new perspective on dissipative cat qubits by reconsidering the reservoir mode used to engineer the tailored two-photon dissipation, and show how it can be leveraged to mitigate gate-induced errors. Doing so, we introduce four new designs of high-fidelity and bias-preserving cat qubit gates, and compare them to the prevalent gate methods. These four designs should give a broad overview of gate engineering for dissipative systems with different and complementary ideas. In particular, we propose both already achievable low-error gate designs and longer-term implementations.
{"title":"Designing High-Fidelity Zeno Gates for Dissipative Cat Qubits","authors":"Gautier, Ronan, Mirrahimi, Mazyar, Sarlette, Alain","doi":"10.1103/prxquantum.4.040316","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040316","url":null,"abstract":"Bosonic cat qubits stabilized with a driven two-photon dissipation are systems with exponentially biased noise, opening the door to low-overhead, fault-tolerant and universal quantum computing. However, current gate proposals for such qubits induce substantial noise of the unprotected type, whose poor scaling with the relevant experimental parameters limits their practical use. In this work, we provide a new perspective on dissipative cat qubits by reconsidering the reservoir mode used to engineer the tailored two-photon dissipation, and show how it can be leveraged to mitigate gate-induced errors. Doing so, we introduce four new designs of high-fidelity and bias-preserving cat qubit gates, and compare them to the prevalent gate methods. These four designs should give a broad overview of gate engineering for dissipative systems with different and complementary ideas. In particular, we propose both already achievable low-error gate designs and longer-term implementations.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"60 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134972235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-24DOI: 10.1103/prxquantum.4.040315
Paul C. Jerger, Yu-Xin Wang, Mykyta Onizhuk, Benjamin S. Soloway, Michael T. Solomon, Christopher Egerstrom, F. Joseph Heremans, Giulia Galli, Aashish A. Clerk, David D. Awschalom
Single-qubit sensing protocols can be used to measure qubit-bath coupling parameters. However, for sufficiently large coupling, the sensing protocol itself perturbs the bath, which is predicted to result in a characteristic response in the sensing measurements. Here, we observe this bath perturbation, also known as a quantum quench, by preparing the nuclear spin bath of a nitrogen-vacancy (NV) center in polarized initial states and performing phase-resolved spin-echo measurements on the NV electron spin. These measurements reveal a time-dependent phase determined by the initial state of the bath. We derive the relationship between the sensor phase and the Gaussian spin-bath polarization and apply it to reconstruct both the axial and transverse polarization components. Using this insight, we optimize the transfer efficiency of our dynamic nuclear polarization sequence. This technique for directly measuring bath polarization may assist in preparing high-fidelity quantum memory states, improving nanoscale NMR methods, and investigating non-Gaussian quantum baths.Received 3 March 2023Accepted 25 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040315Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNV centersQuantum sensingPhysical SystemsDiamondQuantum spin modelsPropertiesSpinTechniquesDynamic nuclear polarizationOptically detected magnetic resonanceSpin noise spectroscopyCondensed Matter, Materials & Applied PhysicsQuantum Information, Science & Technology
{"title":"Detecting Spin-Bath Polarization with Quantum Quench Phase Shifts of Single Spins in Diamond","authors":"Paul C. Jerger, Yu-Xin Wang, Mykyta Onizhuk, Benjamin S. Soloway, Michael T. Solomon, Christopher Egerstrom, F. Joseph Heremans, Giulia Galli, Aashish A. Clerk, David D. Awschalom","doi":"10.1103/prxquantum.4.040315","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040315","url":null,"abstract":"Single-qubit sensing protocols can be used to measure qubit-bath coupling parameters. However, for sufficiently large coupling, the sensing protocol itself perturbs the bath, which is predicted to result in a characteristic response in the sensing measurements. Here, we observe this bath perturbation, also known as a quantum quench, by preparing the nuclear spin bath of a nitrogen-vacancy (NV) center in polarized initial states and performing phase-resolved spin-echo measurements on the NV electron spin. These measurements reveal a time-dependent phase determined by the initial state of the bath. We derive the relationship between the sensor phase and the Gaussian spin-bath polarization and apply it to reconstruct both the axial and transverse polarization components. Using this insight, we optimize the transfer efficiency of our dynamic nuclear polarization sequence. This technique for directly measuring bath polarization may assist in preparing high-fidelity quantum memory states, improving nanoscale NMR methods, and investigating non-Gaussian quantum baths.Received 3 March 2023Accepted 25 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040315Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNV centersQuantum sensingPhysical SystemsDiamondQuantum spin modelsPropertiesSpinTechniquesDynamic nuclear polarizationOptically detected magnetic resonanceSpin noise spectroscopyCondensed Matter, Materials & Applied PhysicsQuantum Information, Science & Technology","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"3 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135273442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-20DOI: 10.1103/prxquantum.4.040314
V. Esteso, R. Duquennoy, R.C. Ng, M. Colautti, P. Lombardi, G. Arregui, E. Chavez-Angel, C.M. Sotomayor-Torres, P.D. Garcia, M. Hilke, C. Toninelli
An understanding of heat transport is relevant to developing efficient strategies for thermal management in areas of study such as microelectronics, as well as for fundamental science purposes. However, the measurement of temperatures in nanostructured environments and in cryogenic conditions remains a challenging task, requiring both high sensitivity and noninvasive approaches. Here, we present a portable nanothermometer based on a molecular two-level quantum system that operates in the (3–20)-K temperature range, with temperatures and spatial resolutions on the order of millikelvins and micrometers, respectively. We validate the performance of this molecular thermometer by estimating the thermal conductivity of a nanopatterned silicon membrane, where we find a quadratic temperature dependence. In addition, we demonstrate two-dimensional temperature mapping via the simultaneous spectroscopy of multiple probes deposited onto such a suspended membrane. Overall, these results demonstrate the unique potential of the proposed molecular thermometer to explore thermal properties with submicron accuracy and unveil related phenomena manifested at cryogenic temperatures.2 MoreReceived 22 February 2023Revised 3 July 2023Accepted 2 August 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040314Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAtomic & molecular processes in external fieldsMolecular spectraSpontaneous emissionAtomic, Molecular & Optical
{"title":"Quantum Thermometry with Single Molecules in Nanoprobes","authors":"V. Esteso, R. Duquennoy, R.C. Ng, M. Colautti, P. Lombardi, G. Arregui, E. Chavez-Angel, C.M. Sotomayor-Torres, P.D. Garcia, M. Hilke, C. Toninelli","doi":"10.1103/prxquantum.4.040314","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040314","url":null,"abstract":"An understanding of heat transport is relevant to developing efficient strategies for thermal management in areas of study such as microelectronics, as well as for fundamental science purposes. However, the measurement of temperatures in nanostructured environments and in cryogenic conditions remains a challenging task, requiring both high sensitivity and noninvasive approaches. Here, we present a portable nanothermometer based on a molecular two-level quantum system that operates in the (3–20)-K temperature range, with temperatures and spatial resolutions on the order of millikelvins and micrometers, respectively. We validate the performance of this molecular thermometer by estimating the thermal conductivity of a nanopatterned silicon membrane, where we find a quadratic temperature dependence. In addition, we demonstrate two-dimensional temperature mapping via the simultaneous spectroscopy of multiple probes deposited onto such a suspended membrane. Overall, these results demonstrate the unique potential of the proposed molecular thermometer to explore thermal properties with submicron accuracy and unveil related phenomena manifested at cryogenic temperatures.2 MoreReceived 22 February 2023Revised 3 July 2023Accepted 2 August 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040314Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAtomic & molecular processes in external fieldsMolecular spectraSpontaneous emissionAtomic, Molecular & Optical","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-18DOI: 10.1103/prxquantum.4.040312
Kohei Kawabata, Zhenyu Xiao, Tomi Ohtsuki, Ryuichi Shindou
The spectral statistics of non-Hermitian random matrices are of importance as a diagnostic tool for chaotic behavior in open quantum systems. Here, we investigate the statistical properties of singular values in non-Hermitian random matrices as an effective measure of quantifying dissipative quantum chaos. By means of Hermitization, we reveal the unique characteristics of the singular-value statistics that distinguish them from the complex-eigenvalue statistics, and establish the comprehensive classification of the singular-value statistics for all the 38-fold symmetry classes of non-Hermitian random matrices. We also analytically derive the singular-value statistics of small random matrices, which well describe those of large random matrices in the similar spirit to the Wigner surmise. Furthermore, we demonstrate that singular values of open quantum many-body systems follow the random-matrix statistics, thereby identifying chaos and nonintegrability in open quantum systems. Our work elucidates that the singular-value statistics serve as a clear indicator of symmetry and lay a foundation for statistical physics of open quantum systems.Received 16 July 2023Accepted 20 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040312Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasOpen quantum systemsQuantum chaosQuantum correlations, foundations & formalismQuantum statistical mechanicsPhysical SystemsNon-Hermitian systemsTechniquesLindblad equationRandom matrix theorySymmetries in condensed matterCondensed Matter, Materials & Applied PhysicsStatistical Physics & ThermodynamicsQuantum Information, Science & TechnologyAtomic, Molecular & Optical
{"title":"Singular-Value Statistics of Non-Hermitian Random Matrices and Open Quantum Systems","authors":"Kohei Kawabata, Zhenyu Xiao, Tomi Ohtsuki, Ryuichi Shindou","doi":"10.1103/prxquantum.4.040312","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040312","url":null,"abstract":"The spectral statistics of non-Hermitian random matrices are of importance as a diagnostic tool for chaotic behavior in open quantum systems. Here, we investigate the statistical properties of singular values in non-Hermitian random matrices as an effective measure of quantifying dissipative quantum chaos. By means of Hermitization, we reveal the unique characteristics of the singular-value statistics that distinguish them from the complex-eigenvalue statistics, and establish the comprehensive classification of the singular-value statistics for all the 38-fold symmetry classes of non-Hermitian random matrices. We also analytically derive the singular-value statistics of small random matrices, which well describe those of large random matrices in the similar spirit to the Wigner surmise. Furthermore, we demonstrate that singular values of open quantum many-body systems follow the random-matrix statistics, thereby identifying chaos and nonintegrability in open quantum systems. Our work elucidates that the singular-value statistics serve as a clear indicator of symmetry and lay a foundation for statistical physics of open quantum systems.Received 16 July 2023Accepted 20 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040312Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasOpen quantum systemsQuantum chaosQuantum correlations, foundations & formalismQuantum statistical mechanicsPhysical SystemsNon-Hermitian systemsTechniquesLindblad equationRandom matrix theorySymmetries in condensed matterCondensed Matter, Materials & Applied PhysicsStatistical Physics & ThermodynamicsQuantum Information, Science & TechnologyAtomic, Molecular & Optical","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135883690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-17DOI: 10.1103/prxquantum.4.040311
Robin Harper, Steven T. Flammia
Building error-corrected quantum computers relies crucially on measuring and modeling noise on candidate devices. In particular, optimal error correction requires knowing the noise that occurs in the device as it executes the circuits required for error correction. As devices increase in size, we will become more reliant on efficient models of this noise. However, such models must still retain the information required to optimize the algorithms used for error correction. Here, we propose a method of extracting detailed information of the noise in a device running syndrome extraction circuits. We introduce and execute an experiment on a superconducting device using 39 of its qubits in a surface code doing repeated rounds of syndrome extraction but omitting the midcircuit measurement and reset. We show how to extract from the 20 data qubits the information needed to build noise models of various sophistication in the form of graphical models. These models give efficient descriptions of noise in large-scale devices and are designed to illuminate the effectiveness of error correction against correlated noise. Our estimates are furthermore precise: we learn a consistent global distribution where all one- and two-qubit error rates are known to a relative error of 0.1%. By extrapolating our experimentally learned noise models toward lower error rates, we demonstrate that accurate correlated noise models are increasingly important for successfully predicting subthreshold behavior in quantum error-correction experiments.4 MoreReceived 18 April 2023Accepted 29 August 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040311Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasQuantum circuitsQuantum correlations in quantum informationQuantum error correctionQuantum information theoryQuantum Information, Science & Technology
{"title":"Learning Correlated Noise in a 39-Qubit Quantum Processor","authors":"Robin Harper, Steven T. Flammia","doi":"10.1103/prxquantum.4.040311","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040311","url":null,"abstract":"Building error-corrected quantum computers relies crucially on measuring and modeling noise on candidate devices. In particular, optimal error correction requires knowing the noise that occurs in the device as it executes the circuits required for error correction. As devices increase in size, we will become more reliant on efficient models of this noise. However, such models must still retain the information required to optimize the algorithms used for error correction. Here, we propose a method of extracting detailed information of the noise in a device running syndrome extraction circuits. We introduce and execute an experiment on a superconducting device using 39 of its qubits in a surface code doing repeated rounds of syndrome extraction but omitting the midcircuit measurement and reset. We show how to extract from the 20 data qubits the information needed to build noise models of various sophistication in the form of graphical models. These models give efficient descriptions of noise in large-scale devices and are designed to illuminate the effectiveness of error correction against correlated noise. Our estimates are furthermore precise: we learn a consistent global distribution where all one- and two-qubit error rates are known to a relative error of 0.1%. By extrapolating our experimentally learned noise models toward lower error rates, we demonstrate that accurate correlated noise models are increasingly important for successfully predicting subthreshold behavior in quantum error-correction experiments.4 MoreReceived 18 April 2023Accepted 29 August 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040311Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasQuantum circuitsQuantum correlations in quantum informationQuantum error correctionQuantum information theoryQuantum Information, Science & Technology","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136033450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-16DOI: 10.1103/prxquantum.4.040310
P. Renault, J. Nokkala, G. Roeland, N.Y. Joly, R. Zambrini, S. Maniscalco, J. Piilo, N. Treps, V. Parigi
A continuous-variable optical setup is used to simulate the open-system quantum dynamics with engineered environments, with applications in quantum biology, synchronization, and understanding the quantum-to-classical transition.
{"title":"Experimental Optical Simulator of Reconfigurable and Complex Quantum Environment","authors":"P. Renault, J. Nokkala, G. Roeland, N.Y. Joly, R. Zambrini, S. Maniscalco, J. Piilo, N. Treps, V. Parigi","doi":"10.1103/prxquantum.4.040310","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040310","url":null,"abstract":"A continuous-variable optical setup is used to simulate the open-system quantum dynamics with engineered environments, with applications in quantum biology, synchronization, and understanding the quantum-to-classical transition.","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136116746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-13DOI: 10.1103/prxquantum.4.040309
Aaron J. Friedman, Oliver Hart, Rahul Nandkishore
We explore universality and phases of matter in hybrid quantum dynamics combining chaotic time evolution and projective measurements. We develop a unitary representation of measurements based on the Stinespring theorem, which we crucially identify with the time evolution of the system and measurement apparatus, affording significant technical advantages and conceptual insight into hybrid dynamics. We diagnose spectral properties in the presence of measurements for the first time, along with standard, experimentally tractable probes of phase structure, finding no nontrivial effects due to measurements in the absence of feedback. We also establish that nonlinearity in the density matrix is neither sufficient nor necessary to see a transition, and instead identify utilization of the measurement outcomes (i.e., “feedback”) as the crucial ingredient. After reviewing the definition of a phase of matter, we identify nontrivial orders in adaptive hybrid dynamics—in which measurement outcomes determine future unitary gates—finding a genuine measurement-induced absorbing-state phase transition in an adaptive quantum East model. In general, we find that only deterministic and constrained Haar-random dynamics with active feedback and without continuous symmetries can realize genuine, measurement-induced phases of matter.2 MoreReceived 31 October 2022Revised 28 May 2023Accepted 18 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040309Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDynamical phase transitionsNonequilibrium statistical mechanicsQuantum chaosQuantum entanglementQuantum feedbackQuantum measurementsPhysical Systems1-dimensional spin chainsFloquet systemsQuantum spin modelsTechniquesQuantum spin chainsAtomic, Molecular & OpticalCondensed Matter, Materials & Applied PhysicsQuantum Information, Science & TechnologyStatistical Physics & Thermodynamics
{"title":"Measurement-Induced Phases of Matter Require Feedback","authors":"Aaron J. Friedman, Oliver Hart, Rahul Nandkishore","doi":"10.1103/prxquantum.4.040309","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040309","url":null,"abstract":"We explore universality and phases of matter in hybrid quantum dynamics combining chaotic time evolution and projective measurements. We develop a unitary representation of measurements based on the Stinespring theorem, which we crucially identify with the time evolution of the system and measurement apparatus, affording significant technical advantages and conceptual insight into hybrid dynamics. We diagnose spectral properties in the presence of measurements for the first time, along with standard, experimentally tractable probes of phase structure, finding no nontrivial effects due to measurements in the absence of feedback. We also establish that nonlinearity in the density matrix is neither sufficient nor necessary to see a transition, and instead identify utilization of the measurement outcomes (i.e., “feedback”) as the crucial ingredient. After reviewing the definition of a phase of matter, we identify nontrivial orders in adaptive hybrid dynamics—in which measurement outcomes determine future unitary gates—finding a genuine measurement-induced absorbing-state phase transition in an adaptive quantum East model. In general, we find that only deterministic and constrained Haar-random dynamics with active feedback and without continuous symmetries can realize genuine, measurement-induced phases of matter.2 MoreReceived 31 October 2022Revised 28 May 2023Accepted 18 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040309Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDynamical phase transitionsNonequilibrium statistical mechanicsQuantum chaosQuantum entanglementQuantum feedbackQuantum measurementsPhysical Systems1-dimensional spin chainsFloquet systemsQuantum spin modelsTechniquesQuantum spin chainsAtomic, Molecular & OpticalCondensed Matter, Materials & Applied PhysicsQuantum Information, Science & TechnologyStatistical Physics & Thermodynamics","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135918518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-12DOI: 10.1103/prxquantum.4.040308
G. Kestler, K. Ton, D. Filin, C. Cheung, P. Schneeweiss, T. Hoinkes, J. Volz, M.S. Safronova, A. Rauschenbeutel, J.T. Barreiro
Neutral atoms that are optically trapped using the evanescent fields surrounding optical nanofibers are a promising platform for developing quantum technologies and exploring fundamental science, such as quantum networks and many-body physics of interacting photons. Building on the successful advancements with trapped alkali atoms, here we trap strontium-88 atoms, an alkaline-earth element, in a state-insensitive, nanofiber-based optical dipole trap using the evanescent fields of an optical nanofiber. Employing a two-color, double magic-wavelength trapping scheme, we realize state-insensitive trapping of the atoms for the kilohertz-wide 5s21S0−5s5p3P1,|m|=1 intercombination transition, which we verify by performing high-resolution spectroscopy for an atom-surface distance of about 300 nm. This allows us to experimentally find and verify the state insensitivity of the trap nearby a theoretically predicted magic wavelength of 435.827(25) nm, a necessary step to confirm precision atomic physics calculations. Alkaline-earth atoms also exhibit nonmagnetic ground states and ultranarrow linewidth transitions making them ideal candidates for atomic clocks and precision metrology applications, especially with state-insensitive traps. Additionally, given the low collisional scattering length specific to strontium-88, this work also lays the foundation for developing versatile and robust matter-wave atomtronic circuits over nanophotonic waveguides.9 MoreReceived 7 February 2023Accepted 7 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040308Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCooling & trappingLight-matter interactionPhotonicsPropertiesPolarizabilityAtomic, Molecular & OpticalQuantum Information, Science & Technology
{"title":"State-Insensitive Trapping of Alkaline-Earth Atoms in a Nanofiber-Based Optical Dipole Trap","authors":"G. Kestler, K. Ton, D. Filin, C. Cheung, P. Schneeweiss, T. Hoinkes, J. Volz, M.S. Safronova, A. Rauschenbeutel, J.T. Barreiro","doi":"10.1103/prxquantum.4.040308","DOIUrl":"https://doi.org/10.1103/prxquantum.4.040308","url":null,"abstract":"Neutral atoms that are optically trapped using the evanescent fields surrounding optical nanofibers are a promising platform for developing quantum technologies and exploring fundamental science, such as quantum networks and many-body physics of interacting photons. Building on the successful advancements with trapped alkali atoms, here we trap strontium-88 atoms, an alkaline-earth element, in a state-insensitive, nanofiber-based optical dipole trap using the evanescent fields of an optical nanofiber. Employing a two-color, double magic-wavelength trapping scheme, we realize state-insensitive trapping of the atoms for the kilohertz-wide 5s21S0−5s5p3P1,|m|=1 intercombination transition, which we verify by performing high-resolution spectroscopy for an atom-surface distance of about 300 nm. This allows us to experimentally find and verify the state insensitivity of the trap nearby a theoretically predicted magic wavelength of 435.827(25) nm, a necessary step to confirm precision atomic physics calculations. Alkaline-earth atoms also exhibit nonmagnetic ground states and ultranarrow linewidth transitions making them ideal candidates for atomic clocks and precision metrology applications, especially with state-insensitive traps. Additionally, given the low collisional scattering length specific to strontium-88, this work also lays the foundation for developing versatile and robust matter-wave atomtronic circuits over nanophotonic waveguides.9 MoreReceived 7 February 2023Accepted 7 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040308Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasCooling & trappingLight-matter interactionPhotonicsPropertiesPolarizabilityAtomic, Molecular & OpticalQuantum Information, Science & Technology","PeriodicalId":74587,"journal":{"name":"PRX quantum : a Physical Review journal","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136012623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-11DOI: 10.1103/prxquantum.4.040307
Eleftherios-Ermis Tselentis, Ämin Baumeler
It is well known that if one assumes quantum theory to hold locally, then processes with indefinite causal order and cyclic causal structures become feasible. Here we study qualitative limitations on causal structures and correlations imposed by local quantum theory. We find a necessary graph-theoretic criterion—the “siblings-on-cycles” property—for a causal structure to be admissible: only such causal structures admit a realization consistent with local quantum theory. We conjecture that this property is moreover sufficient. This conjecture is motivated by an explicit construction of quantum causal models, and is supported by numerical calculations. We show that these causal models, in a restricted setting, are indeed consistent. We identify two sets of causal structures that, in the classical-deterministic case, forbid and give rise to noncausal correlations, respectively.Received 17 January 2023Accepted 8 September 2023DOI:https://doi.org/10.1103/PRXQuantum.4.040307Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasGeneral relativityPhysics of computationQuantum communicationQuantum controlQuantum correlations in quantum informationQuantum correlations, foundations & formalismQuantum foundationsQuantum gravityQuantum networksRelativistic quantum informationSpacetime topology & causal structureQuantum Information, Science & TechnologyInterdisciplinary PhysicsGravitation, Cosmology & Astrophysics
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