Pub Date : 2024-10-26DOI: 10.1038/s42005-024-01838-9
Jiameng Wang, Arthur Ernst, Victor N. Antonov, Qi Jiang, Haoji Qian, Deyang Wang, Jiefeng Cao, Fangyuan Zhu, Shan Qiao, Mao Ye
Recently discovered Mn-based kagome materials, such as RMn6Sn6 (R = rare-earth element), exhibit the coexistence of topological electronic states and long-range magnetic order, offering a platform for studying quantum phenomena. However, understanding the electronic and magnetic properties of these materials remains incomplete. Here, we investigate the electronic structure and magnetic properties of GdMn6Sn6 using x-ray magnetic circular dichroism, photoemission spectroscopy, and theoretical calculations. We observe localized electronic states from spin frustration in the Mn-based kagome lattice and induced magnetic moments in the nonmagnetic element Sn experimentally, which originate from the Sn- $$p$$ and Mn- $$d$$ orbital hybridization. Our calculations also reveal ferromagnetic coupling within the kagome Mn-Mn layer, driven by double exchange interaction. This work provides insights into the mechanisms of magnetic interaction and magnetic tuning in the exploration of topological quantum materials. Mn-based kagome materials like RMn6Sn6 (R = rare-earth element) exhibit topological states and long-range magnetic order. This work demonstrates the ferrimagnetic structure in GdMn6Sn6, revealing induced magnetic moments in nonmagnetic Sn, and Mn-Mn double exchange interaction mediated by Sn atoms.
最近发现的锰基卡戈米材料，如 RMn6Sn6（R = 稀土元素），表现出拓扑电子态与长程磁序共存的特性，为研究量子现象提供了一个平台。然而，对这些材料的电子和磁性能的了解仍不全面。在这里，我们利用 X 射线磁圆二色性、光发射光谱和理论计算研究了 GdMn6Sn6 的电子结构和磁性能。我们通过实验观察到锰基卡戈米晶格中自旋挫折产生的局部电子态，以及非磁性元素 Sn 中的诱导磁矩，这些磁矩来自 Sn- p 和 Mn- d 轨道杂化。我们的计算还揭示了卡戈米锰锰层内由双交换相互作用驱动的铁磁耦合。这项工作为探索拓扑量子材料中的磁相互作用和磁调谐机制提供了见解。
{"title":"Double exchange interaction in Mn-based topological kagome ferrimagnet","authors":"Jiameng Wang, Arthur Ernst, Victor N. Antonov, Qi Jiang, Haoji Qian, Deyang Wang, Jiefeng Cao, Fangyuan Zhu, Shan Qiao, Mao Ye","doi":"10.1038/s42005-024-01838-9","DOIUrl":"10.1038/s42005-024-01838-9","url":null,"abstract":"Recently discovered Mn-based kagome materials, such as RMn6Sn6 (R = rare-earth element), exhibit the coexistence of topological electronic states and long-range magnetic order, offering a platform for studying quantum phenomena. However, understanding the electronic and magnetic properties of these materials remains incomplete. Here, we investigate the electronic structure and magnetic properties of GdMn6Sn6 using x-ray magnetic circular dichroism, photoemission spectroscopy, and theoretical calculations. We observe localized electronic states from spin frustration in the Mn-based kagome lattice and induced magnetic moments in the nonmagnetic element Sn experimentally, which originate from the Sn- $$p$$ and Mn- $$d$$ orbital hybridization. Our calculations also reveal ferromagnetic coupling within the kagome Mn-Mn layer, driven by double exchange interaction. This work provides insights into the mechanisms of magnetic interaction and magnetic tuning in the exploration of topological quantum materials. Mn-based kagome materials like RMn6Sn6 (R = rare-earth element) exhibit topological states and long-range magnetic order. This work demonstrates the ferrimagnetic structure in GdMn6Sn6, revealing induced magnetic moments in nonmagnetic Sn, and Mn-Mn double exchange interaction mediated by Sn atoms.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11512815/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142521251","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}
Phase change materials have been widely exploited in active metasurfaces due to their large index contrast. Despite recent advances in phase-change metasurfaces, it remains a challenge to integrate diverse reconfigurable optical functionalities into a single metasurface. Here, we demonstrate an effective strategy to realize reconfigurable wavefront control by combining a Ge2Sb2Te5-rod array with laser writing technology. Through arbitrarily modifying the position and power of laser source, the laser writing process helps to realize site-selective and multi-level phase change of Ge2Sb2Te5 rods. Due to multi-level switching for optical properties of Ge2Sb2Te5 material, the Ge2Sb2Te5-rod array offers complete phase control and high amplitude modulation. Subsequently, various optical devices are designed in numerical simulation, including a phase-only hologram, dynamic meta-deflectors, a grayscale image and a perfect absorber. The structured Ge2Sb2Te5-based metasurface with the combination of laser writing technology offers an effective way to explore various types of optical functionalities in the same device. A tunable metasurface exhibiting dynamically optical functionalities is highly desired in practice. Here, the authors demonstrate a dynamically reconfigurable metasurface by combining the Ge2Sb2Te5-rod array with laser engineering technology, for which various optical functionalities can be randomly and reversibly written and erased.
{"title":"Laser-induced reconfigurable wavefront control with a structured Ge2Sb2Te5-based metasurface","authors":"Sha Hu, Chao Wang, Shuo Du, Zhuoxuan Han, Nannan Hu, Changzhi Gu","doi":"10.1038/s42005-024-01846-9","DOIUrl":"10.1038/s42005-024-01846-9","url":null,"abstract":"Phase change materials have been widely exploited in active metasurfaces due to their large index contrast. Despite recent advances in phase-change metasurfaces, it remains a challenge to integrate diverse reconfigurable optical functionalities into a single metasurface. Here, we demonstrate an effective strategy to realize reconfigurable wavefront control by combining a Ge2Sb2Te5-rod array with laser writing technology. Through arbitrarily modifying the position and power of laser source, the laser writing process helps to realize site-selective and multi-level phase change of Ge2Sb2Te5 rods. Due to multi-level switching for optical properties of Ge2Sb2Te5 material, the Ge2Sb2Te5-rod array offers complete phase control and high amplitude modulation. Subsequently, various optical devices are designed in numerical simulation, including a phase-only hologram, dynamic meta-deflectors, a grayscale image and a perfect absorber. The structured Ge2Sb2Te5-based metasurface with the combination of laser writing technology offers an effective way to explore various types of optical functionalities in the same device. A tunable metasurface exhibiting dynamically optical functionalities is highly desired in practice. Here, the authors demonstrate a dynamically reconfigurable metasurface by combining the Ge2Sb2Te5-rod array with laser engineering technology, for which various optical functionalities can be randomly and reversibly written and erased.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-6"},"PeriodicalIF":5.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01846-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525740","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 : 2024-10-25DOI: 10.1038/s42005-024-01837-w
Vaiva Vasiliauskaite, Nino Antulov-Fantulin
Differential equations are a ubiquitous tool to study dynamics, ranging from physical systems to complex systems, where a large number of agents interact through a graph. Data-driven approximations of differential equations present a promising alternative to traditional methods for uncovering a model of dynamical systems, especially in complex systems that lack explicit first principles. A recently employed machine learning tool for studying dynamics is neural networks, which can be used for solution finding or discovery of differential equations. However, deploying deep learning models in unfamiliar settings-such as predicting dynamics in unobserved state space regions or on novel graphs-can lead to spurious results. Focusing on complex systems whose dynamics are described with a system of first-order differential equations coupled through a graph, we study generalization of neural network predictions in settings where statistical properties of test data and training data are different. We find that neural networks can accurately predict dynamics beyond the immediate training setting within the domain of the training data. To identify when a model is unable to generalize to novel settings, we propose a statistical significance test. Deep learning is a promising alternative to traditional methods for discovering governing equations, such as variational and perturbation methods, or data-driven approaches like symbolic regression. This paper explores the generalization of neural approximations of dynamics on complex networks to novel, unobserved settings and proposes a statistical testing framework to quantify confidence in the inferred predictions.
{"title":"Generalization of neural network models for complex network dynamics","authors":"Vaiva Vasiliauskaite, Nino Antulov-Fantulin","doi":"10.1038/s42005-024-01837-w","DOIUrl":"10.1038/s42005-024-01837-w","url":null,"abstract":"Differential equations are a ubiquitous tool to study dynamics, ranging from physical systems to complex systems, where a large number of agents interact through a graph. Data-driven approximations of differential equations present a promising alternative to traditional methods for uncovering a model of dynamical systems, especially in complex systems that lack explicit first principles. A recently employed machine learning tool for studying dynamics is neural networks, which can be used for solution finding or discovery of differential equations. However, deploying deep learning models in unfamiliar settings-such as predicting dynamics in unobserved state space regions or on novel graphs-can lead to spurious results. Focusing on complex systems whose dynamics are described with a system of first-order differential equations coupled through a graph, we study generalization of neural network predictions in settings where statistical properties of test data and training data are different. We find that neural networks can accurately predict dynamics beyond the immediate training setting within the domain of the training data. To identify when a model is unable to generalize to novel settings, we propose a statistical significance test. Deep learning is a promising alternative to traditional methods for discovering governing equations, such as variational and perturbation methods, or data-driven approaches like symbolic regression. This paper explores the generalization of neural approximations of dynamics on complex networks to novel, unobserved settings and proposes a statistical testing framework to quantify confidence in the inferred predictions.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01837-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525722","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 : 2024-10-25DOI: 10.1038/s42005-024-01841-0
Byoung-moo Ann, Gary A. Steele
It is known that the electromagnetic vacuum is responsible for the Lamb shift, which is a crucial phenomenon in quantum electrodynamics (QED). In circuit QED, the readout or bus resonators that are dispersively coupled can result in a significant Lamb shift of the qubit. However, previous approaches or proposals for controlling the Lamb shift in circuit QED demand overheads in circuit designs or non-perturbative renormalization of the system’s eigenbases, which can impose formidable limitations. In this work, we propose and demonstrate an all-microwave method for controlling the Lamb shift of fixed-frequency transmons. We employ the drive-induced longitudinal coupling between the transmon and resonator. By simply using an off-resonant monochromatic drive near the resonator frequency, we can control the net Lamb shift up to ±30 MHz and engineer it to zero with the drive-induced longitudinal coupling without facing the aforementioned challenges. Our work establishes an efficient way of engineering the fundamental effects of the electromagnetic vacuum and provides greater flexibility in non-parametric frequency controls of multilevel systems. Engineering the Lamb shifts of superconducting qubits opens new opportunities in resonant frequency tunings and other applications. Here, the authors devise and demonstrate an all-microwave approach that can be utilized with fixed-frequency superconducting qubits.
众所周知，电磁真空造成了量子电动力学（QED）中的一个重要现象--兰姆位移。在电路 QED 中，色散耦合的读出或总线谐振器会导致量子比特发生显著的 Lamb 偏移。然而，以往在电路 QED 中控制兰姆位移的方法或建议需要电路设计的开销或系统特征基的非微扰重规范化，这可能会带来巨大的限制。在这项工作中，我们提出并演示了一种全微波方法，用于控制固定频率跨子的兰姆位移。我们采用了跨子和谐振器之间的驱动诱导纵向耦合。只需在谐振器频率附近使用非谐振单色驱动器，我们就能控制高达±30 MHz的净兰姆偏移，并利用驱动器诱导的纵向耦合将其设计为零，而无需面对上述挑战。我们的工作确立了一种有效的电磁真空基本效应工程方法，并为多级系统的非参数频率控制提供了更大的灵活性。超导量子比特的 Lamb shifts 工程为谐振频率调谐和其他应用带来了新的机遇。在此，作者设计并演示了一种可用于固定频率超导量子比特的全微波方法。
{"title":"All-microwave Lamb shift engineering for a fixed frequency multi-level superconducting qubit","authors":"Byoung-moo Ann, Gary A. Steele","doi":"10.1038/s42005-024-01841-0","DOIUrl":"10.1038/s42005-024-01841-0","url":null,"abstract":"It is known that the electromagnetic vacuum is responsible for the Lamb shift, which is a crucial phenomenon in quantum electrodynamics (QED). In circuit QED, the readout or bus resonators that are dispersively coupled can result in a significant Lamb shift of the qubit. However, previous approaches or proposals for controlling the Lamb shift in circuit QED demand overheads in circuit designs or non-perturbative renormalization of the system’s eigenbases, which can impose formidable limitations. In this work, we propose and demonstrate an all-microwave method for controlling the Lamb shift of fixed-frequency transmons. We employ the drive-induced longitudinal coupling between the transmon and resonator. By simply using an off-resonant monochromatic drive near the resonator frequency, we can control the net Lamb shift up to ±30 MHz and engineer it to zero with the drive-induced longitudinal coupling without facing the aforementioned challenges. Our work establishes an efficient way of engineering the fundamental effects of the electromagnetic vacuum and provides greater flexibility in non-parametric frequency controls of multilevel systems. Engineering the Lamb shifts of superconducting qubits opens new opportunities in resonant frequency tunings and other applications. Here, the authors devise and demonstrate an all-microwave approach that can be utilized with fixed-frequency superconducting qubits.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-6"},"PeriodicalIF":5.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01841-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525700","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}
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}
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