Recent advancements of quantum technologies have triggered tremendous interest in exploring practical quantum advantage. The simulation of fluid dynamics, a highly challenging problem in classical physics but vital for practical applications, emerges as a potential direction. Here, we report an experiment on the digital simulation of unsteady flows with a superconducting quantum processor. The quantum algorithm is based on the Hamiltonian simulation using the hydrodynamic formulation of the Schrödinger equation. With the median fidelities of 99.97% and 99.67% for parallel single- and two-qubit gates respectively, we simulate the dynamics of a two-dimensional (2D) compressible diverging flow and a 2D decaying vortex with ten qubits. Note that the former case is an inviscid potential flow, and the latter one is an artificial vortical flow with an external body force. The experimental results well capture the temporal evolution of averaged density and momentum profiles, and qualitatively reproduce spatial flow fields with moderate noises. This work demonstrates the potential of quantum computing in simulating more complex flows, such as turbulence, for practical applications. Fluid dynamics simulation, a complex challenge in classical physics, is relevant for real-world applications and highlights the potential of quantum computing. The authors report an experiment for the digital simulation of unsteady flows on a superconducting quantum processor, and show that the results effectively capture the evolution of flow fields.
{"title":"Simulating unsteady flows on a superconducting quantum processor","authors":"Zhaoyuan Meng, Jiarun Zhong, Shibo Xu, Ke Wang, Jiachen Chen, Feitong Jin, Xuhao Zhu, Yu Gao, Yaozu Wu, Chuanyu Zhang, Ning Wang, Yiren Zou, Aosai Zhang, Zhengyi Cui, Fanhao Shen, Zehang Bao, Zitian Zhu, Ziqi Tan, Tingting Li, Pengfei Zhang, Shiying Xiong, Hekang Li, Qiujiang Guo, Zhen Wang, Chao Song, H. Wang, Yue Yang","doi":"10.1038/s42005-024-01845-w","DOIUrl":"10.1038/s42005-024-01845-w","url":null,"abstract":"Recent advancements of quantum technologies have triggered tremendous interest in exploring practical quantum advantage. The simulation of fluid dynamics, a highly challenging problem in classical physics but vital for practical applications, emerges as a potential direction. Here, we report an experiment on the digital simulation of unsteady flows with a superconducting quantum processor. The quantum algorithm is based on the Hamiltonian simulation using the hydrodynamic formulation of the Schrödinger equation. With the median fidelities of 99.97% and 99.67% for parallel single- and two-qubit gates respectively, we simulate the dynamics of a two-dimensional (2D) compressible diverging flow and a 2D decaying vortex with ten qubits. Note that the former case is an inviscid potential flow, and the latter one is an artificial vortical flow with an external body force. The experimental results well capture the temporal evolution of averaged density and momentum profiles, and qualitatively reproduce spatial flow fields with moderate noises. This work demonstrates the potential of quantum computing in simulating more complex flows, such as turbulence, for practical applications. Fluid dynamics simulation, a complex challenge in classical physics, is relevant for real-world applications and highlights the potential of quantum computing. The authors report an experiment for the digital simulation of unsteady flows on a superconducting quantum processor, and show that the results effectively capture the evolution of flow fields.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-7"},"PeriodicalIF":5.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01845-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525705","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 : 2024-10-22DOI: 10.1038/s42005-024-01827-y
Iván Coarasa, Julio Amaré, Jaime Apilluelo, Susana Cebrián, David Cintas, Eduardo García, María Martínez, Miguel Ángel Oliván, Ysrael Ortigoza, Alfonso Ortiz de Solórzano, Tamara Pardo, Jorge Puimedón, Ana Salinas, María Luisa Sarsa, Patricia Villar
Weakly interacting massive particles (WIMPs) are well-motivated candidates for dark matter. One signature of galactic WIMPs is the annual modulation expected in a detector’s interaction rate, which arises from Earth’s revolution around the Sun. Over two decades, the DAMA/LIBRA experiment has observed such modulation with 250 kg of NaI(Tl) scintillators, in accordance with WIMP expectations but inconsistent with the negative results of other experiments. The signal depends on the target material, so to validate or refute the DAMA result, the experiment must be replicated using the same material. This is the goal of the ANAIS–112 experiment, currently underway since August 2017 with 112.5 kg of NaI(Tl). In this work, we present a reanalysis of three years of data employing an improved analysis chain to enhance the experimental sensitivity. The results presented here are consistent with the absence of modulation and inconsistent with DAMA’s observation at nearly 3σ confidence level, with the potential to reach a 5σ level within 8 years from the beginning of the data collection. Additionally, we explore the impact of different scintillation quenching factors in the comparison between ANAIS–112 and DAMA/LIBRA. The DAMA/LIBRA experiment has observed a clear signal of dark matter for over 20 years. Although this signal contradicts the negative results of other experiments, it cannot be dismissed without replication using the same material. The authors present the negative results from the ANAIS-112 experiment, which uses the same target and shows strong tension with DAMA/LIBRA
{"title":"ANAIS–112 three years data: a sensitive model independent negative test of the DAMA/LIBRA dark matter signal","authors":"Iván Coarasa, Julio Amaré, Jaime Apilluelo, Susana Cebrián, David Cintas, Eduardo García, María Martínez, Miguel Ángel Oliván, Ysrael Ortigoza, Alfonso Ortiz de Solórzano, Tamara Pardo, Jorge Puimedón, Ana Salinas, María Luisa Sarsa, Patricia Villar","doi":"10.1038/s42005-024-01827-y","DOIUrl":"10.1038/s42005-024-01827-y","url":null,"abstract":"Weakly interacting massive particles (WIMPs) are well-motivated candidates for dark matter. One signature of galactic WIMPs is the annual modulation expected in a detector’s interaction rate, which arises from Earth’s revolution around the Sun. Over two decades, the DAMA/LIBRA experiment has observed such modulation with 250 kg of NaI(Tl) scintillators, in accordance with WIMP expectations but inconsistent with the negative results of other experiments. The signal depends on the target material, so to validate or refute the DAMA result, the experiment must be replicated using the same material. This is the goal of the ANAIS–112 experiment, currently underway since August 2017 with 112.5 kg of NaI(Tl). In this work, we present a reanalysis of three years of data employing an improved analysis chain to enhance the experimental sensitivity. The results presented here are consistent with the absence of modulation and inconsistent with DAMA’s observation at nearly 3σ confidence level, with the potential to reach a 5σ level within 8 years from the beginning of the data collection. Additionally, we explore the impact of different scintillation quenching factors in the comparison between ANAIS–112 and DAMA/LIBRA. The DAMA/LIBRA experiment has observed a clear signal of dark matter for over 20 years. Although this signal contradicts the negative results of other experiments, it cannot be dismissed without replication using the same material. The authors present the negative results from the ANAIS-112 experiment, which uses the same target and shows strong tension with DAMA/LIBRA","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-12"},"PeriodicalIF":5.4,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01827-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525714","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 : 2024-10-21DOI: 10.1038/s42005-024-01833-0
Rezvan Tahouri, Asimina Papoulia, Stefanos Carlström, Felipe Zapata, Jan Marcus Dahlström
The development in attosecond physics allows for unprecedented control of atoms and molecules in the time domain. Here, ultrashort pulses are used to prepare atomic ions in specific magnetic states, which may be important for controlling charge migration in molecules. Our work fills the knowledge gap of relativistic hole alignment prepared by femtosecond and attosecond pulses. The research focuses on optimizing the central frequency and duration of pulses to exploit specific spectral features, such as Fano profiles, Cooper minima, and giant resonances. Simulations are performed using the Relativistic Time-Dependent Configuration-Interaction Singles method. Ultrafast hole alignment with large ratios (on the order of one hundred) is observed in the outer-shell hole of argon. An even larger alignment (on the order of one thousand) is observed in the inner-shell hole of xenon. In this work, the authors investigate the distribution of holes with different magnetic quantum numbers in noble gas atoms, ionized by femtosecond and attosecond pulses. They achieve high control over hole alignment by adjusting pulse parameters and exploiting specific spectral features.
{"title":"Relativistic treatment of hole alignment in noble gas atoms","authors":"Rezvan Tahouri, Asimina Papoulia, Stefanos Carlström, Felipe Zapata, Jan Marcus Dahlström","doi":"10.1038/s42005-024-01833-0","DOIUrl":"10.1038/s42005-024-01833-0","url":null,"abstract":"The development in attosecond physics allows for unprecedented control of atoms and molecules in the time domain. Here, ultrashort pulses are used to prepare atomic ions in specific magnetic states, which may be important for controlling charge migration in molecules. Our work fills the knowledge gap of relativistic hole alignment prepared by femtosecond and attosecond pulses. The research focuses on optimizing the central frequency and duration of pulses to exploit specific spectral features, such as Fano profiles, Cooper minima, and giant resonances. Simulations are performed using the Relativistic Time-Dependent Configuration-Interaction Singles method. Ultrafast hole alignment with large ratios (on the order of one hundred) is observed in the outer-shell hole of argon. An even larger alignment (on the order of one thousand) is observed in the inner-shell hole of xenon. In this work, the authors investigate the distribution of holes with different magnetic quantum numbers in noble gas atoms, ionized by femtosecond and attosecond pulses. They achieve high control over hole alignment by adjusting pulse parameters and exploiting specific spectral features.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01833-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525737","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 : 2024-10-21DOI: 10.1038/s42005-024-01835-y
Lorenzo Caprini, Davide Breoni, Anton Ldov, Christian Scholz, Hartmut Löwen
Dynamical clustering is a key feature of active matter systems composed of self-propelled agents that convert environmental energy into mechanical motion. At the micron scale, where overdamped dynamics dominate, particles with opposite motility can obstruct each other’s movement, leading to transient dynamical arrest. This arrest can promote cluster formation and motility-induced phase separation. However, in macroscopic agents, where inertia plays a significant role, clustering is heavily influenced by bounce-back effects during collisions, which can impede cluster growth. Here we present an experiment based on active granular particles, in which inertia can be systematically tuned by changing the shaker frequency. As a result, a set of phenomena driven and controlled by inertia emerges. Before the suppression of clustering, inertia induces a transition in the cluster’s inner structure. For small inertia, clusters are characterized by the crystalline order typical of overdamped particles, while for large inertia clusters with liquid-like order are observed. In addition, in contrast to microswimmers, where active particles wet the boundary by primarily forming clusters attached to the container walls, in an underdamped inertial active system, walls do not favor cluster formation and effectively annihilate motility-induced wetting phenomena. As a consequence, inertia suppresses cluster nucleation at the system boundaries. Active matter systems composed of self-propelled agents exhibit dynamical clustering. In this work, the authors demonstrate that inertia induces a solid-liquid transition within the cluster structure and suppresses wetting phenomena at the container boundary.
{"title":"Dynamical clustering and wetting phenomena in inertial active matter","authors":"Lorenzo Caprini, Davide Breoni, Anton Ldov, Christian Scholz, Hartmut Löwen","doi":"10.1038/s42005-024-01835-y","DOIUrl":"10.1038/s42005-024-01835-y","url":null,"abstract":"Dynamical clustering is a key feature of active matter systems composed of self-propelled agents that convert environmental energy into mechanical motion. At the micron scale, where overdamped dynamics dominate, particles with opposite motility can obstruct each other’s movement, leading to transient dynamical arrest. This arrest can promote cluster formation and motility-induced phase separation. However, in macroscopic agents, where inertia plays a significant role, clustering is heavily influenced by bounce-back effects during collisions, which can impede cluster growth. Here we present an experiment based on active granular particles, in which inertia can be systematically tuned by changing the shaker frequency. As a result, a set of phenomena driven and controlled by inertia emerges. Before the suppression of clustering, inertia induces a transition in the cluster’s inner structure. For small inertia, clusters are characterized by the crystalline order typical of overdamped particles, while for large inertia clusters with liquid-like order are observed. In addition, in contrast to microswimmers, where active particles wet the boundary by primarily forming clusters attached to the container walls, in an underdamped inertial active system, walls do not favor cluster formation and effectively annihilate motility-induced wetting phenomena. As a consequence, inertia suppresses cluster nucleation at the system boundaries. Active matter systems composed of self-propelled agents exhibit dynamical clustering. In this work, the authors demonstrate that inertia induces a solid-liquid transition within the cluster structure and suppresses wetting phenomena at the container boundary.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-11"},"PeriodicalIF":5.4,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01835-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525748","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 : 2024-10-18DOI: 10.1038/s42005-024-01798-0
Rui Mao, Guojing Tian, Xiaoming Sun
In quantum chemistry, the variational quantum eigensolver (VQE) is a promising algorithm for molecular simulations on near-term quantum computers. However, VQEs using hardware-efficient circuits face scaling challenges due to the barren plateau problem. This raises the question of whether chemically inspired circuits from unitary coupled cluster (UCC) methods can avoid this issue. Here we provide theoretical evidence indicating they may not. By examining alternated dUCC ansätzes and relaxed Trotterized UCC ansätzes, we find that in the infinite depth limit, a separation occurs between particle-hole one- and two-body unitary operators. While one-body terms yield a polynomially concentrated energy landscape, adding two-body terms leads to exponential concentration. Numerical simulations support these findings, suggesting that popular 1-step Trotterized unitary coupled-cluster with singles and doubles (UCCSD) ansätze may not scale. Our results emphasize the link between trainability and circuit expressiveness, raising doubts about VQEs’ ability to surpass classical methods. The variational quantum eigensolver (VQE) is a promising approach for molecular simulations on quantum computers but faces scaling issues due to the barren plateau problem. The authors’ findings indicate that unitary coupled cluster circuits may not overcome these challenges, raising doubts about VQE’s ability to outperform classical methods.
{"title":"Towards determining the presence of barren plateaus in some chemically inspired variational quantum algorithms","authors":"Rui Mao, Guojing Tian, Xiaoming Sun","doi":"10.1038/s42005-024-01798-0","DOIUrl":"10.1038/s42005-024-01798-0","url":null,"abstract":"In quantum chemistry, the variational quantum eigensolver (VQE) is a promising algorithm for molecular simulations on near-term quantum computers. However, VQEs using hardware-efficient circuits face scaling challenges due to the barren plateau problem. This raises the question of whether chemically inspired circuits from unitary coupled cluster (UCC) methods can avoid this issue. Here we provide theoretical evidence indicating they may not. By examining alternated dUCC ansätzes and relaxed Trotterized UCC ansätzes, we find that in the infinite depth limit, a separation occurs between particle-hole one- and two-body unitary operators. While one-body terms yield a polynomially concentrated energy landscape, adding two-body terms leads to exponential concentration. Numerical simulations support these findings, suggesting that popular 1-step Trotterized unitary coupled-cluster with singles and doubles (UCCSD) ansätze may not scale. Our results emphasize the link between trainability and circuit expressiveness, raising doubts about VQEs’ ability to surpass classical methods. The variational quantum eigensolver (VQE) is a promising approach for molecular simulations on quantum computers but faces scaling issues due to the barren plateau problem. The authors’ findings indicate that unitary coupled cluster circuits may not overcome these challenges, raising doubts about VQE’s ability to outperform classical methods.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01798-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525717","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 : 2024-10-17DOI: 10.1038/s42005-024-01804-5
Eetu Pelimanni, Adam E. A. Fouda, Phay J. Ho, Thomas M. Baumann, Sergey I. Bokarev, Alberto De Fanis, Simon Dold, Gilbert Grell, Iyas Ismail, Dimitrios Koulentianos, Tommaso Mazza, Michael Meyer, Maria-Novella Piancastelli, Ralph Püttner, Daniel E. Rivas, Björn Senfftleben, Marc Simon, Linda Young, Gilles Doumy
The ultrashort and intense pulses of X-rays produced at X-ray free electron lasers (XFELs) have enabled unique experiments on the atomic level structure and dynamics of matter, with time-resolved studies permitted in the femto- and attosecond regimes. To fully exploit them, it is paramount to obtain a comprehensive understanding of the complex nonlinear interactions that can occur at such extreme X-ray intensities. Herein, we report on the experimental observation of a resonant double-core excitation scheme in N2, where two 1σ core-level electrons are resonantly promoted to unoccupied $$1{pi }_{g}^{* }$$ molecular orbitals by a single few-femtosecond broad-bandwidth XFEL pulse. The production of these neutral two-site double core hole states is evidenced through their characteristic decay channels, which are observed in good agreement with high-level theoretical calculations. Such multi-core excitation schemes, benefiting from the high interaction cross sections and state- and site-selective nature of resonant X-ray interactions, should be generally accessible in XFEL irradiated molecules, and provide interesting opportunities for chemical analysis and for monitoring ultrafast dynamic processes. XFELs can drive multicore-ionization/excitation processes in the fs timescale of typical core-hole lifetimes in molecules. This paper reports experimental evidence of a single XFEL-pulse-driven resonant double-core excitation mechanism, producing a neutral two-site double-core-hole state in the nitrogen molecule.
X 射线自由电子激光器（XFEL）产生的超短和高强度 X 射线脉冲使我们能够对物质的原子级结构和动力学进行独特的实验，并允许在飞秒和阿秒级进行时间分辨研究。要充分利用它们，最重要的是全面了解在这种极端 X 射线强度下可能发生的复杂非线性相互作用。在这里，我们报告了对 N2 中共振双核激发方案的实验观察，在该方案中，两个 1σ 核级电子通过单个几皮秒宽带 XFEL 脉冲共振促进到未被占用的 $$1{pi }_{g}^{* }$$ 分子轨道。这些中性双位双核空穴态的产生通过其特征衰变通道得到了证明，其观测结果与高水平理论计算结果十分吻合。这种多核激发方案得益于高相互作用截面以及共振 X 射线相互作用的状态和位点选择性，应该可以在 XFEL 照射的分子中普遍应用，并为化学分析和监测超快动态过程提供了有趣的机会。XFEL 可以在分子中典型核孔寿命的 fs 时间尺度内驱动多核电离/激发过程。本文报告了单个 XFEL 脉冲驱动的共振双核激发机制的实验证据，该机制在氮分子中产生了中性双位双核空穴态。
{"title":"Observation of molecular resonant double-core excitation driven by intense X-ray pulses","authors":"Eetu Pelimanni, Adam E. A. Fouda, Phay J. Ho, Thomas M. Baumann, Sergey I. Bokarev, Alberto De Fanis, Simon Dold, Gilbert Grell, Iyas Ismail, Dimitrios Koulentianos, Tommaso Mazza, Michael Meyer, Maria-Novella Piancastelli, Ralph Püttner, Daniel E. Rivas, Björn Senfftleben, Marc Simon, Linda Young, Gilles Doumy","doi":"10.1038/s42005-024-01804-5","DOIUrl":"10.1038/s42005-024-01804-5","url":null,"abstract":"The ultrashort and intense pulses of X-rays produced at X-ray free electron lasers (XFELs) have enabled unique experiments on the atomic level structure and dynamics of matter, with time-resolved studies permitted in the femto- and attosecond regimes. To fully exploit them, it is paramount to obtain a comprehensive understanding of the complex nonlinear interactions that can occur at such extreme X-ray intensities. Herein, we report on the experimental observation of a resonant double-core excitation scheme in N2, where two 1σ core-level electrons are resonantly promoted to unoccupied $$1{pi }_{g}^{* }$$ molecular orbitals by a single few-femtosecond broad-bandwidth XFEL pulse. The production of these neutral two-site double core hole states is evidenced through their characteristic decay channels, which are observed in good agreement with high-level theoretical calculations. Such multi-core excitation schemes, benefiting from the high interaction cross sections and state- and site-selective nature of resonant X-ray interactions, should be generally accessible in XFEL irradiated molecules, and provide interesting opportunities for chemical analysis and for monitoring ultrafast dynamic processes. XFELs can drive multicore-ionization/excitation processes in the fs timescale of typical core-hole lifetimes in molecules. This paper reports experimental evidence of a single XFEL-pulse-driven resonant double-core excitation mechanism, producing a neutral two-site double-core-hole state in the nitrogen molecule.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01804-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443612","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}
Parity-time (PT) symmetry has enabled the demonstration of fascinating wave phenomena in non-Hermitian systems characterized by precisely balanced gain and loss. Until now, the exploration and observation of PT symmetry in scattering settings have largely been limited to propagating waves. Here, we demonstrate a versatile coupled-resonator acoustic waveguide (CRAW) system that enables the observation of PT-symmetric scattering responses for evanescent waves within a bandgap. By examining the generalized scattering matrix in the evanescent wave regime, we observe hallmark PT-symmetric phenomena—including phase transitions at an exceptional point, anisotropic transmission resonances, and laser-absorber modes—in systems that do not require balanced distributions of gain and loss. Owing to the peculiar energy transfer features of evanescent waves, our results not only demonstrate a distinct pathway for observing PT symmetry, but also enable strategies for exotic energy tunneling mechanisms, paving fresh directions for wave engineering grounded in non-Hermitian physics. Non-Hermitian physics and parity-time (PT) symmetry are of broad interest in classical wave systems. This work demonstrates evanescent wave manipulation and scattering control based on PT symmetry in a versatile coupled-resonator acoustic waveguide (CRAW) system, which not only extends the framework of non-Hermitian physics but also offers strategies for near-field manipulation and control.
{"title":"Observation of parity-time symmetry for evanescent waves","authors":"Zhaoxian Chen, Huan He, Huanan Li, Meijie Li, Jun-long Kou, Yan-qing Lu, Jingjun Xu, Andrea Alù","doi":"10.1038/s42005-024-01816-1","DOIUrl":"10.1038/s42005-024-01816-1","url":null,"abstract":"Parity-time (PT) symmetry has enabled the demonstration of fascinating wave phenomena in non-Hermitian systems characterized by precisely balanced gain and loss. Until now, the exploration and observation of PT symmetry in scattering settings have largely been limited to propagating waves. Here, we demonstrate a versatile coupled-resonator acoustic waveguide (CRAW) system that enables the observation of PT-symmetric scattering responses for evanescent waves within a bandgap. By examining the generalized scattering matrix in the evanescent wave regime, we observe hallmark PT-symmetric phenomena—including phase transitions at an exceptional point, anisotropic transmission resonances, and laser-absorber modes—in systems that do not require balanced distributions of gain and loss. Owing to the peculiar energy transfer features of evanescent waves, our results not only demonstrate a distinct pathway for observing PT symmetry, but also enable strategies for exotic energy tunneling mechanisms, paving fresh directions for wave engineering grounded in non-Hermitian physics. Non-Hermitian physics and parity-time (PT) symmetry are of broad interest in classical wave systems. This work demonstrates evanescent wave manipulation and scattering control based on PT symmetry in a versatile coupled-resonator acoustic waveguide (CRAW) system, which not only extends the framework of non-Hermitian physics but also offers strategies for near-field manipulation and control.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01816-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443620","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 : 2024-10-15DOI: 10.1038/s42005-024-01832-1
Xiao Xue, Shuo Wang, Hua-Dong Yao, Lars Davidson, Peter V. Coveney
Data-driven approaches offer novel opportunities for improving the performance of turbulent flow simulations, which are critical to wide-ranging applications from wind farms and aerodynamic designs to weather and climate forecasting. However, current methods for these simulations often require large amounts of data and computational resources. While data-driven methods have been extensively applied to the continuum Navier-Stokes equations, limited work has been done to integrate these methods with the highly scalable lattice Boltzmann method. Here, we present a physics-informed neural network framework for improving lattice Boltzmann-based simulations of near-wall turbulent flow. Using a small amount of data and integrating physical constraints, our model accurately predicts flow behaviour at a wide range of friction Reynolds numbers up to 1.0 × 106. In contradistinction with other models that use direct numerical simulation datasets, this approach reduces data requirements by three orders of magnitude and allows for sparse grid configurations. Our work broadens the scope of lattice Boltzmann applications, enabling efficient large-scale simulations of turbulent flow in diverse contexts. The authors provide a data-driven near-wall modelling framework for the lattice Boltzmann method using IDDES data. Their model can predict flows with friction Reynolds numbers up to 1,000,000 and effectively handle sparse near-wall grids.
{"title":"Physics informed data-driven near-wall modelling for lattice Boltzmann simulation of high Reynolds number turbulent flows","authors":"Xiao Xue, Shuo Wang, Hua-Dong Yao, Lars Davidson, Peter V. Coveney","doi":"10.1038/s42005-024-01832-1","DOIUrl":"10.1038/s42005-024-01832-1","url":null,"abstract":"Data-driven approaches offer novel opportunities for improving the performance of turbulent flow simulations, which are critical to wide-ranging applications from wind farms and aerodynamic designs to weather and climate forecasting. However, current methods for these simulations often require large amounts of data and computational resources. While data-driven methods have been extensively applied to the continuum Navier-Stokes equations, limited work has been done to integrate these methods with the highly scalable lattice Boltzmann method. Here, we present a physics-informed neural network framework for improving lattice Boltzmann-based simulations of near-wall turbulent flow. Using a small amount of data and integrating physical constraints, our model accurately predicts flow behaviour at a wide range of friction Reynolds numbers up to 1.0 × 106. In contradistinction with other models that use direct numerical simulation datasets, this approach reduces data requirements by three orders of magnitude and allows for sparse grid configurations. Our work broadens the scope of lattice Boltzmann applications, enabling efficient large-scale simulations of turbulent flow in diverse contexts. The authors provide a data-driven near-wall modelling framework for the lattice Boltzmann method using IDDES data. Their model can predict flows with friction Reynolds numbers up to 1,000,000 and effectively handle sparse near-wall grids.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01832-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443634","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}
Spin-orbitronics, exploiting electron spin and/or orbital angular momentum, offers a powerful route to energy-efficient spintronic applications. Recent research on orbital currents in light metals broadens the scope of spin-orbit torque (SOT). However, distinguishing and manipulating orbital torque in heavy metal/ferromagnet (HM/FM) remains a challenge, limiting the promising synergy of spin and orbital currents. Here, we design a HM/FM/FMSOC heterostructure and experimentally separate orbital torque contribution from spin torque by utilizing the distinct diffusion length of spin and orbital currents. Furthermore, we achieve the synergy of spin and orbital torques by controlling their relative strength, and obtain a 110% improvement in torque efficiency compared to the representative Pt/Co bilayer. Our findings not only contribute to a deeper understanding of SOT mechanisms and orbital current transport in HM/FM multilayers, but also highlight the promising prospect of orbital and spin torque synergy for optimizing the efficiency of next-generation spintronic devices. Eliminating the interference of spin current to distinguish and manipulate orbital torque in heavy metal/ferromagnet (HM/FM) heterojunction remains a challenge. Here, the authors design a HM/FM/FMSOC multilayer to separate orbital torque contribution and harness the synergy of spin and orbital currents for enhanced spin-orbit torque.
自旋轨道电子学利用电子自旋和/或轨道角动量，为高能效自旋电子学应用提供了一条强大的途径。最近对轻金属中轨道电流的研究拓宽了自旋轨道力矩（SOT）的范围。然而，在重金属/铁磁体（HM/FM）中区分和操纵轨道力矩仍然是一个挑战，限制了自旋和轨道电流的协同作用。在这里，我们设计了一种 HM/FM/FMSOC 异质结构，并利用自旋电流和轨道电流不同的扩散长度，通过实验将轨道转矩贡献从自旋转矩中分离出来。此外，我们还通过控制自旋扭矩和轨道扭矩的相对强度来实现它们的协同作用，与具有代表性的铂/钴双层结构相比，扭矩效率提高了 110%。我们的发现不仅有助于加深对 HM/FM 多层中的 SOT 机制和轨道电流传输的理解，还凸显了轨道扭矩和自旋扭矩协同作用在优化下一代自旋电子器件效率方面的广阔前景。消除自旋电流的干扰以区分和操纵重金属/铁磁体（HM/FM）异质结中的轨道力矩仍然是一项挑战。在此，作者设计了一种 HM/FM/FMSOC 多层，以分离轨道力矩的贡献，并利用自旋和轨道电流的协同作用来增强自旋轨道力矩。
{"title":"Harnessing synergy of spin and orbital currents in heavy metal/ferromagnet multilayers","authors":"Yumin Yang, Zhicheng Xie, Zhiyuan Zhao, Na Lei, Jianhua Zhao, Dahai Wei","doi":"10.1038/s42005-024-01829-w","DOIUrl":"10.1038/s42005-024-01829-w","url":null,"abstract":"Spin-orbitronics, exploiting electron spin and/or orbital angular momentum, offers a powerful route to energy-efficient spintronic applications. Recent research on orbital currents in light metals broadens the scope of spin-orbit torque (SOT). However, distinguishing and manipulating orbital torque in heavy metal/ferromagnet (HM/FM) remains a challenge, limiting the promising synergy of spin and orbital currents. Here, we design a HM/FM/FMSOC heterostructure and experimentally separate orbital torque contribution from spin torque by utilizing the distinct diffusion length of spin and orbital currents. Furthermore, we achieve the synergy of spin and orbital torques by controlling their relative strength, and obtain a 110% improvement in torque efficiency compared to the representative Pt/Co bilayer. Our findings not only contribute to a deeper understanding of SOT mechanisms and orbital current transport in HM/FM multilayers, but also highlight the promising prospect of orbital and spin torque synergy for optimizing the efficiency of next-generation spintronic devices. Eliminating the interference of spin current to distinguish and manipulate orbital torque in heavy metal/ferromagnet (HM/FM) heterojunction remains a challenge. Here, the authors design a HM/FM/FMSOC multilayer to separate orbital torque contribution and harness the synergy of spin and orbital currents for enhanced spin-orbit torque.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01829-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443633","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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