Pub Date : 2024-07-13DOI: 10.1038/s42005-024-01715-5
Chun-Xiao Liu, A. Mert Bozkurt, Francesco Zatelli, Sebastiaan L. D. ten Haaf, Tom Dvir, Michael Wimmer
Connecting double quantum dots via a semiconductor-superconductor hybrid segment offers a platform for creating a two-site Kitaev chain that hosts Majorana zero modes at a finely tuned sweet spot. However, the effective couplings mediated by Andreev bound states in the hybrid are generally weak in the tunneling regime. As a consequence, the excitation gap is limited in size, presenting a formidable challenge for using this platform to demonstrate non-Abelian statistics and realize topological quantum computing. Here we systematically study the effects of increasing the dot-hybrid coupling. In particular, the proximity effect transforms the dot orbitals into Yu-Shiba-Rusinov states, and as the coupling strength increases, the excitation gap is significantly enhanced and sensitivity to local perturbation is reduced. We also discuss how the strong-coupling regime shows in experimentally accessible quantities, such as conductance, and provide a protocol for tuning a double-dot system into a sweet spot with a large excitation gap. A quantum dot-superconductor array can form a Kitaev chain which hosts Majorana zero modes at a sweet spot. The authors examine how to enhance the excitation gap of the Majorana zero modes, which is crucial for implementing topological quantum computing with enhanced protection.
{"title":"Enhancing the excitation gap of a quantum-dot-based Kitaev chain","authors":"Chun-Xiao Liu, A. Mert Bozkurt, Francesco Zatelli, Sebastiaan L. D. ten Haaf, Tom Dvir, Michael Wimmer","doi":"10.1038/s42005-024-01715-5","DOIUrl":"10.1038/s42005-024-01715-5","url":null,"abstract":"Connecting double quantum dots via a semiconductor-superconductor hybrid segment offers a platform for creating a two-site Kitaev chain that hosts Majorana zero modes at a finely tuned sweet spot. However, the effective couplings mediated by Andreev bound states in the hybrid are generally weak in the tunneling regime. As a consequence, the excitation gap is limited in size, presenting a formidable challenge for using this platform to demonstrate non-Abelian statistics and realize topological quantum computing. Here we systematically study the effects of increasing the dot-hybrid coupling. In particular, the proximity effect transforms the dot orbitals into Yu-Shiba-Rusinov states, and as the coupling strength increases, the excitation gap is significantly enhanced and sensitivity to local perturbation is reduced. We also discuss how the strong-coupling regime shows in experimentally accessible quantities, such as conductance, and provide a protocol for tuning a double-dot system into a sweet spot with a large excitation gap. A quantum dot-superconductor array can form a Kitaev chain which hosts Majorana zero modes at a sweet spot. The authors examine how to enhance the excitation gap of the Majorana zero modes, which is crucial for implementing topological quantum computing with enhanced protection.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01715-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141610159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-13DOI: 10.1038/s42005-024-01724-4
Chenjun Wu, Toshihiro Omori, Takuji Ishikawa
Controlling microrobot locomotion in vessels and capillaries is crucial for precise drug delivery and minimally invasive surgeries. However, this is challenging due to the complex interactions with red blood cells (RBCs) and the difficulty navigating within the dense environment. Here, we construct a numerical framework to evaluate the relative resistance coefficient ( $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ ) of a microrobot propelled through RBC suspensions. Our experiments validate the numerical results. We find that $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ increases for smaller microrobots and higher hematocrit levels, while magnetic force strength weakly impacts $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ . $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ is smaller than the resistance coefficient of a macroscale robot estimated from the apparent viscosity of the RBC suspension. The aspect ratio of a prolate ellipsoidal microrobot influences $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ along its long-axis direction. Additionally, machine learning accurately predicts $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ . These insights could enhance the design and control of microrobots for medical applications. Controlling microrobot movement in blood vessels is vital for medical treatments but is challenging due to red blood cells. This study combines simulations, experiments, and machine learning to demonstrate how hematocrit levels and robot geometry affect its locomotion characteristics in blood
{"title":"Drag force on a microrobot propelled through blood","authors":"Chenjun Wu, Toshihiro Omori, Takuji Ishikawa","doi":"10.1038/s42005-024-01724-4","DOIUrl":"10.1038/s42005-024-01724-4","url":null,"abstract":"Controlling microrobot locomotion in vessels and capillaries is crucial for precise drug delivery and minimally invasive surgeries. However, this is challenging due to the complex interactions with red blood cells (RBCs) and the difficulty navigating within the dense environment. Here, we construct a numerical framework to evaluate the relative resistance coefficient ( $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ ) of a microrobot propelled through RBC suspensions. Our experiments validate the numerical results. We find that $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ increases for smaller microrobots and higher hematocrit levels, while magnetic force strength weakly impacts $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ . $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ is smaller than the resistance coefficient of a macroscale robot estimated from the apparent viscosity of the RBC suspension. The aspect ratio of a prolate ellipsoidal microrobot influences $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ along its long-axis direction. Additionally, machine learning accurately predicts $${C}_{{{{{{{{rm{r}}}}}}}}}^{* }$$ . These insights could enhance the design and control of microrobots for medical applications. Controlling microrobot movement in blood vessels is vital for medical treatments but is challenging due to red blood cells. This study combines simulations, experiments, and machine learning to demonstrate how hematocrit levels and robot geometry affect its locomotion characteristics in blood","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01724-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1038/s42005-024-01733-3
Aashish Sah, Suman Kundu, Heikki Suominen, Qiming Chen, Mikko Möttönen
Achieving fast gates and long coherence times for superconducting qubits presents challenges, typically requiring either a stronger coupling of the drive line or an excessively strong microwave signal to the qubit. To address this, we introduce on-chip filters of the qubit drive exhibiting a stopband at the qubit frequency, thus enabling long coherence times and strong coupling at the subharmonic frequency, facilitating fast single-qubit gates, and reduced thermal load. The filters exhibit an extrinsic relaxation time of a few seconds while enabling sub-10-ns gates with subharmonic control. Here we show up to 200-fold improvement in the measured relaxation time at the stopband. Furthermore, we implement subharmonic driving of Rabi oscillations with a π pulse duration of 12 ns. Our demonstration of on-chip filters and efficient subharmonic driving in a two-dimensional quantum processor paves the way for a scalable qubit architecture with reduced thermal load and noise from the control line. Qubit development demands two conflicting requirements: good isolation from the environment and yet a strong coupling with control drive lines. This work addresses this issue, by implementing an on-chip filter that decouples a superconducting qubit from resonant modes of the environments, while achieving strong coupling with low-frequency modes.
{"title":"Decay-protected superconducting qubit with fast control enabled by integrated on-chip filters","authors":"Aashish Sah, Suman Kundu, Heikki Suominen, Qiming Chen, Mikko Möttönen","doi":"10.1038/s42005-024-01733-3","DOIUrl":"10.1038/s42005-024-01733-3","url":null,"abstract":"Achieving fast gates and long coherence times for superconducting qubits presents challenges, typically requiring either a stronger coupling of the drive line or an excessively strong microwave signal to the qubit. To address this, we introduce on-chip filters of the qubit drive exhibiting a stopband at the qubit frequency, thus enabling long coherence times and strong coupling at the subharmonic frequency, facilitating fast single-qubit gates, and reduced thermal load. The filters exhibit an extrinsic relaxation time of a few seconds while enabling sub-10-ns gates with subharmonic control. Here we show up to 200-fold improvement in the measured relaxation time at the stopband. Furthermore, we implement subharmonic driving of Rabi oscillations with a π pulse duration of 12 ns. Our demonstration of on-chip filters and efficient subharmonic driving in a two-dimensional quantum processor paves the way for a scalable qubit architecture with reduced thermal load and noise from the control line. Qubit development demands two conflicting requirements: good isolation from the environment and yet a strong coupling with control drive lines. This work addresses this issue, by implementing an on-chip filter that decouples a superconducting qubit from resonant modes of the environments, while achieving strong coupling with low-frequency modes.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01733-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1038/s42005-024-01730-6
Jintong Zhao, Zhongxue Gan, Ruixi Huang, Chun Guan, Jifan Shi, Siyang Leng
An abundance of complex dynamical phenomena exists in nature and human society, requiring sophisticated analytical tools to understand and explain. Causal analysis through observational time series data is essential in comprehending complex systems when controlled experiments are not feasible or ethical. Although data-based causal discovery methods have been widely used, there is still a lack of direct ways more aligned with the intuitive definition of causality, i.e., whether interventions on one element lead to changes in the subsequent development of others. To solve this problem, we propose the method of intervened reservoir computing (IRC) based on constructing a neural network replica of the original system and applying interventions to it. This approach enables controlled trials, thus observing the intervened evolution, in the digital twins of the underlying systems. Simulated and real-world data are used to test our approach and demonstrate its accuracy in inferring causal networks. Given the importance of causality in understanding complex dynamics, we anticipate that IRC could serve as a powerful tool for various disciplines to decipher the intrinsic mechanisms of natural systems from observational data. Understanding complex systems requires causal analysis via observational time series, yet there is still a lack of direct ways aligned with the intuitive definition of causality. Here, the authors use reservoir computing to replicate the underlying system and apply interventions to it, enabling controlled trials and accurate causal discovery.
{"title":"Detecting dynamical causality via intervened reservoir computing","authors":"Jintong Zhao, Zhongxue Gan, Ruixi Huang, Chun Guan, Jifan Shi, Siyang Leng","doi":"10.1038/s42005-024-01730-6","DOIUrl":"10.1038/s42005-024-01730-6","url":null,"abstract":"An abundance of complex dynamical phenomena exists in nature and human society, requiring sophisticated analytical tools to understand and explain. Causal analysis through observational time series data is essential in comprehending complex systems when controlled experiments are not feasible or ethical. Although data-based causal discovery methods have been widely used, there is still a lack of direct ways more aligned with the intuitive definition of causality, i.e., whether interventions on one element lead to changes in the subsequent development of others. To solve this problem, we propose the method of intervened reservoir computing (IRC) based on constructing a neural network replica of the original system and applying interventions to it. This approach enables controlled trials, thus observing the intervened evolution, in the digital twins of the underlying systems. Simulated and real-world data are used to test our approach and demonstrate its accuracy in inferring causal networks. Given the importance of causality in understanding complex dynamics, we anticipate that IRC could serve as a powerful tool for various disciplines to decipher the intrinsic mechanisms of natural systems from observational data. Understanding complex systems requires causal analysis via observational time series, yet there is still a lack of direct ways aligned with the intuitive definition of causality. Here, the authors use reservoir computing to replicate the underlying system and apply interventions to it, enabling controlled trials and accurate causal discovery.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01730-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1038/s42005-024-01725-3
Prashant Singh, Karel Proesmans
Measuring entropy production of a system directly from the experimental data is highly desirable since it gives a quantifiable measure of the time-irreversibility for non-equilibrium systems and can be used as a cost function to optimize the performance of the system. Although numerous methods are available to infer the entropy production of stationary systems, there are only a limited number of methods that have been proposed for time-dependent systems and, to the best of our knowledge, none of these methods have been applied to experimental systems. Herein, we develop a general non-invasive methodology to infer a lower bound on the mean total entropy production for arbitrary time-dependent continuous-state Markov systems in terms of the moments of the underlying state variables. The method gives quite accurate estimates for the entropy production, both for theoretical toy models and for experimental bit erasure, even with a very limited amount of experimental data. Directly measuring entropy production from experimental data without prior knowledge of the underlying model is highly desirable, as it quantifies time-irreversibility in non-equilibrium systems and can be used to optimize system performance. In this work, the authors have developed a general methodology to infer entropy production for arbitrary time-dependent systems from its first few moments. The method gives quite accurate estimates both for theoretical examples as well as for experimental data on bit erasure.
{"title":"Inferring entropy production from time-dependent moments","authors":"Prashant Singh, Karel Proesmans","doi":"10.1038/s42005-024-01725-3","DOIUrl":"10.1038/s42005-024-01725-3","url":null,"abstract":"Measuring entropy production of a system directly from the experimental data is highly desirable since it gives a quantifiable measure of the time-irreversibility for non-equilibrium systems and can be used as a cost function to optimize the performance of the system. Although numerous methods are available to infer the entropy production of stationary systems, there are only a limited number of methods that have been proposed for time-dependent systems and, to the best of our knowledge, none of these methods have been applied to experimental systems. Herein, we develop a general non-invasive methodology to infer a lower bound on the mean total entropy production for arbitrary time-dependent continuous-state Markov systems in terms of the moments of the underlying state variables. The method gives quite accurate estimates for the entropy production, both for theoretical toy models and for experimental bit erasure, even with a very limited amount of experimental data. Directly measuring entropy production from experimental data without prior knowledge of the underlying model is highly desirable, as it quantifies time-irreversibility in non-equilibrium systems and can be used to optimize system performance. In this work, the authors have developed a general methodology to infer entropy production for arbitrary time-dependent systems from its first few moments. The method gives quite accurate estimates both for theoretical examples as well as for experimental data on bit erasure.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01725-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1038/s42005-024-01691-w
Oana Bǎzǎvan, Sebastian Saner, Emanuelle Tirrito, Gabriel Araneda, Raghavendra Srinivas, Alejandro Bermudez
Resource efficient schemes for the quantum simulation of lattice gauge theories can benefit from hybrid encodings of gauge and matter fields that use the native degrees of freedom, such as internal qubits and motional phonons in trapped-ion devices. We propose to use a parametric scheme to induce a tunneling of the phonons conditioned to the internal qubit state which, when implemented with a single trapped ion, corresponds to a minimal $${{mathbb{Z}}}_{2}$$ gauge theory. To evaluate the feasibility of this scheme, we perform numerical simulations of the state-dependent tunneling using realistic parameters, and identify the leading sources of error in future experiments. We discuss how to generalize this minimal case to more complex settings by increasing the number of ions, moving from a single link to a $${{mathbb{Z}}}_{2}$$ plaquette, and to an entire $${{mathbb{Z}}}_{2}$$ chain. We present analytical expressions for the gauge-invariant dynamics and the corresponding confinement, which are benchmarked using matrix product state simulations. An outstanding question for gauge-theory quantum simulators is to find viable schemes that allow one to move from the initial prototypes towards the large-scale regime. In this work, the authors present a detailed toolbox for the quantum simulator of Z2 lattice gauge theories coupled to dynamical matter using trapped-ion systems that can overcome these limitations.
{"title":"Synthetic $${{mathbb{Z}}}_{2}$$ gauge theories based on parametric excitations of trapped ions","authors":"Oana Bǎzǎvan, Sebastian Saner, Emanuelle Tirrito, Gabriel Araneda, Raghavendra Srinivas, Alejandro Bermudez","doi":"10.1038/s42005-024-01691-w","DOIUrl":"10.1038/s42005-024-01691-w","url":null,"abstract":"Resource efficient schemes for the quantum simulation of lattice gauge theories can benefit from hybrid encodings of gauge and matter fields that use the native degrees of freedom, such as internal qubits and motional phonons in trapped-ion devices. We propose to use a parametric scheme to induce a tunneling of the phonons conditioned to the internal qubit state which, when implemented with a single trapped ion, corresponds to a minimal $${{mathbb{Z}}}_{2}$$ gauge theory. To evaluate the feasibility of this scheme, we perform numerical simulations of the state-dependent tunneling using realistic parameters, and identify the leading sources of error in future experiments. We discuss how to generalize this minimal case to more complex settings by increasing the number of ions, moving from a single link to a $${{mathbb{Z}}}_{2}$$ plaquette, and to an entire $${{mathbb{Z}}}_{2}$$ chain. We present analytical expressions for the gauge-invariant dynamics and the corresponding confinement, which are benchmarked using matrix product state simulations. An outstanding question for gauge-theory quantum simulators is to find viable schemes that allow one to move from the initial prototypes towards the large-scale regime. In this work, the authors present a detailed toolbox for the quantum simulator of Z2 lattice gauge theories coupled to dynamical matter using trapped-ion systems that can overcome these limitations.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01691-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1038/s42005-024-01701-x
Izabela Biało, Leonardo Martinelli, Gabriele De Luca, Paul Worm, Annabella Drewanowski, Simon Jöhr, Jaewon Choi, Mirian Garcia-Fernandez, Stefano Agrestini, Ke-Jin Zhou, Kurt Kummer, Nicholas B. Brookes, Luo Guo, Anthony Edgeton, Chang B. Eom, Jan M. Tomczak, Karsten Held, Marta Gibert, Qisi Wang, Johan Chang
Magnetic frustration is a route for novel ground states, including spin liquids and spin ices. Such frustration can be introduced through either lattice geometry or incompatible exchange interactions. Here, we find that epitaxial strain is an effective tool for tuning antiferromagnetic exchange interactions in a square-lattice system. By studying the magnon excitations in La2NiO4 films using resonant inelastic x-ray scattering, we show that the magnon displays substantial dispersion along the antiferromagnetic zone boundary, at energies that depend on the lattice of the film’s substrate. Using first principles simulations and an effective spin model, we demonstrate that the antiferromagnetic next-nearest neighbour coupling is a consequence of the two-orbital nature of La2NiO4. Altogether, we illustrate that compressive epitaxial strain enhances this coupling and, as a result, increases the level of incompatibility between exchange interactions within a model square-lattice system. Frustration in magnetic systems may lead to exotic quantum phases such as spin liquid and spin ice state. Here the authors demonstrate that compressive epitaxial strain in La2NiO4 films deposited on different substrates can tune antiferromagnetic exchange interactions and increase the degree of frustration through the increased level of incompatibility between exchange interactions.
磁沮度是包括自旋液体和自旋冰在内的新型基态的形成途径。这种挫折可以通过晶格几何或不相容的交换相互作用引入。在这里，我们发现外延应变是调整方晶格体系中反铁磁交换相互作用的有效工具。通过使用共振非弹性 X 射线散射来研究 La2NiO4 薄膜中的磁子激发，我们发现磁子沿着反铁磁区边界显示出很大的分散性，其能量取决于薄膜基底的晶格。利用第一原理模拟和有效自旋模型，我们证明了反铁磁性近邻耦合是 La2NiO4 双轨道性质的结果。总之，我们说明了压缩外延应变会增强这种耦合，并因此增加模型方晶格系统内交换相互作用之间的不相容程度。磁性系统中的挫折可能会导致奇异的量子相，如自旋液态和自旋冰态。作者在此证明，沉积在不同基底上的 La2NiO4 薄膜中的压缩外延应变可以调整反铁磁交换相互作用，并通过增加交换相互作用之间的不相容程度来提高挫折程度。
{"title":"Strain-tuned incompatible magnetic exchange-interaction in La2NiO4","authors":"Izabela Biało, Leonardo Martinelli, Gabriele De Luca, Paul Worm, Annabella Drewanowski, Simon Jöhr, Jaewon Choi, Mirian Garcia-Fernandez, Stefano Agrestini, Ke-Jin Zhou, Kurt Kummer, Nicholas B. Brookes, Luo Guo, Anthony Edgeton, Chang B. Eom, Jan M. Tomczak, Karsten Held, Marta Gibert, Qisi Wang, Johan Chang","doi":"10.1038/s42005-024-01701-x","DOIUrl":"10.1038/s42005-024-01701-x","url":null,"abstract":"Magnetic frustration is a route for novel ground states, including spin liquids and spin ices. Such frustration can be introduced through either lattice geometry or incompatible exchange interactions. Here, we find that epitaxial strain is an effective tool for tuning antiferromagnetic exchange interactions in a square-lattice system. By studying the magnon excitations in La2NiO4 films using resonant inelastic x-ray scattering, we show that the magnon displays substantial dispersion along the antiferromagnetic zone boundary, at energies that depend on the lattice of the film’s substrate. Using first principles simulations and an effective spin model, we demonstrate that the antiferromagnetic next-nearest neighbour coupling is a consequence of the two-orbital nature of La2NiO4. Altogether, we illustrate that compressive epitaxial strain enhances this coupling and, as a result, increases the level of incompatibility between exchange interactions within a model square-lattice system. Frustration in magnetic systems may lead to exotic quantum phases such as spin liquid and spin ice state. Here the authors demonstrate that compressive epitaxial strain in La2NiO4 films deposited on different substrates can tune antiferromagnetic exchange interactions and increase the degree of frustration through the increased level of incompatibility between exchange interactions.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01701-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1038/s42005-024-01699-2
J. Küspert, I. Biało, R. Frison, A. Morawietz, L. Martinelli, J. Choi, D. Bucher, O. Ivashko, M. v Zimmermann, N. B. Christensen, D. G. Mazzone, G. Simutis, A. A. Turrini, L. Thomarat, D. W. Tam, M. Janoschek, T. Kurosawa, N. Momono, M. Oda, Qisi Wang, J. Chang
Unconventional superconductivity often couples to other electronic orders in a cooperative or competing fashion. Identifying external stimuli that tune between these two limits is of fundamental interest. Here, we show that strain perpendicular to the copper-oxide planes couples directly to the competing interaction between charge stripe order and superconductivity in La1.88Sr0.12CuO4 (LSCO). Compressive c-axis pressure amplifies stripe order within the superconducting state, while having no impact on the normal state. By contrast, strain dramatically diminishes the magnetic field enhancement of stripe order in the superconducting state. These results suggest that c-axis strain acts as tuning parameter of the competing interaction between charge stripe order and superconductivity. This interpretation implies a uniaxial pressure-induced ground state in which the competition between charge order and superconductivity is reduced. Tuning superconductivity and its interplay with other phases in cuprates yields insights into the underlying physics of this material class. Here, the authors performed a hard x-ray diffraction experiment on La1.88Sr0.12CuO4 showing that uniaxial pressure along the c-axis acts as a direct tuning parameter of the competition between superconductivity and charge order.
非常规超导通常以合作或竞争的方式与其他电子阶耦合。找出能在这两种限制之间进行调整的外部刺激具有重要意义。在这里，我们展示了垂直于氧化铜平面的应变直接耦合到 La1.88Sr0.12CuO4 (LSCO) 中电荷条纹秩序和超导性之间的竞争性相互作用。压缩 c 轴压力放大了超导态中的条纹秩序，而对正常态没有影响。相比之下，应变会显著降低磁场对超导态条纹有序的增强作用。这些结果表明，c 轴应变是电荷条纹有序性和超导性之间竞争性相互作用的调节参数。这种解释意味着在单轴压力诱导的基态中，电荷有序性和超导性之间的竞争会减弱。
{"title":"Engineering phase competition between stripe order and superconductivity in La1.88Sr0.12CuO4","authors":"J. Küspert, I. Biało, R. Frison, A. Morawietz, L. Martinelli, J. Choi, D. Bucher, O. Ivashko, M. v Zimmermann, N. B. Christensen, D. G. Mazzone, G. Simutis, A. A. Turrini, L. Thomarat, D. W. Tam, M. Janoschek, T. Kurosawa, N. Momono, M. Oda, Qisi Wang, J. Chang","doi":"10.1038/s42005-024-01699-2","DOIUrl":"10.1038/s42005-024-01699-2","url":null,"abstract":"Unconventional superconductivity often couples to other electronic orders in a cooperative or competing fashion. Identifying external stimuli that tune between these two limits is of fundamental interest. Here, we show that strain perpendicular to the copper-oxide planes couples directly to the competing interaction between charge stripe order and superconductivity in La1.88Sr0.12CuO4 (LSCO). Compressive c-axis pressure amplifies stripe order within the superconducting state, while having no impact on the normal state. By contrast, strain dramatically diminishes the magnetic field enhancement of stripe order in the superconducting state. These results suggest that c-axis strain acts as tuning parameter of the competing interaction between charge stripe order and superconductivity. This interpretation implies a uniaxial pressure-induced ground state in which the competition between charge order and superconductivity is reduced. Tuning superconductivity and its interplay with other phases in cuprates yields insights into the underlying physics of this material class. Here, the authors performed a hard x-ray diffraction experiment on La1.88Sr0.12CuO4 showing that uniaxial pressure along the c-axis acts as a direct tuning parameter of the competition between superconductivity and charge order.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01699-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141569924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Typical weak signal search experiments rely on resonant effects, where the resonance frequency is scanned over a broad range, resulting in significant time consumption. In this study, we demonstrate an accelerated strategy that surpasses the typical resonance-bandwidth limited scan step without compromising sensitivity. We apply this method to an alkali-noble-gas spin system, achieving an approximately 30-fold increase in scanning step size. Additionally, we obtain an ultrahigh sensitivity of 1.29 fT ⋅ Hz−1/2 at around 5 Hz, corresponding to an energy resolution of approximately 1.8 × 10−23eV ⋅ Hz−1/2, which is among the highest quantum energy resolutions reported. Furthermore, we use this sensor to search for axion-like particles, setting stringent constraints on axion-like particles (ALPs) in the 4.5–15.5 Hz Compton-frequency range coupling to neutrons and protons, improving on previous limits by several-fold. This accelerated strategy has potential applications in other resonant search experiments. Weak signal detection, as in the case for the search of Dark Matter, relies on the resonant effect, when many frequencies are scanner in search of the signal, but this is very time consuming. The authors present a magnetometry method that combines high sensitivity and a wider parameter space coverage adopting an artificially enlarged resonance width, increasing the scanning efficiency.
{"title":"Constraining ultralight dark matter through an accelerated resonant search","authors":"Zitong Xu, Xiaolin Ma, Kai Wei, Yuxuan He, Xing Heng, Xiaofei Huang, Tengyu Ai, Jian Liao, Wei Ji, Jia Liu, Xiao-Ping Wang, Dmitry Budker","doi":"10.1038/s42005-024-01713-7","DOIUrl":"10.1038/s42005-024-01713-7","url":null,"abstract":"Typical weak signal search experiments rely on resonant effects, where the resonance frequency is scanned over a broad range, resulting in significant time consumption. In this study, we demonstrate an accelerated strategy that surpasses the typical resonance-bandwidth limited scan step without compromising sensitivity. We apply this method to an alkali-noble-gas spin system, achieving an approximately 30-fold increase in scanning step size. Additionally, we obtain an ultrahigh sensitivity of 1.29 fT ⋅ Hz−1/2 at around 5 Hz, corresponding to an energy resolution of approximately 1.8 × 10−23eV ⋅ Hz−1/2, which is among the highest quantum energy resolutions reported. Furthermore, we use this sensor to search for axion-like particles, setting stringent constraints on axion-like particles (ALPs) in the 4.5–15.5 Hz Compton-frequency range coupling to neutrons and protons, improving on previous limits by several-fold. This accelerated strategy has potential applications in other resonant search experiments. Weak signal detection, as in the case for the search of Dark Matter, relies on the resonant effect, when many frequencies are scanner in search of the signal, but this is very time consuming. The authors present a magnetometry method that combines high sensitivity and a wider parameter space coverage adopting an artificially enlarged resonance width, increasing the scanning efficiency.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.4,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01713-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141585960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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