The fundamental principle of satellite/node-based positioning involves triangulating the receiver’s coordinates through the intersection of spatial distances. Advancements in hybrid wireless networks have yielded high-precision positioning at decimeter-level (wavelength-level), approaching the resolution limits in free space. Here we present a 3D super-resolution positioning paradigm in free space by utilizing a kind of topologically structured pulses, toroidal electromagnetic pulses. We demonstrate that the space-time nonseparability and skyrmion topology inherent in toroidal pulses can be harnessed to achieve freespace microwave 3D positioning with super-resolution accuracy, reaching the centimeter level, using a single emitting antenna. This work opens up avenues for exploring the potential applications of topological electromagnetic pulses including but not limited to positioning, imaging and sensing technologies. This paper presents a positioning paradigm in free space by utilizing toroidal electromagnetic pulses. The space-time nonseparability and skyrmion topology inherent in toroidal pulses are harnessed to achieve freespace microwave 3D positioning with super-resolution accuracy, reaching the centimeter level, using a single emitting antenna.
{"title":"Single-antenna super-resolution positioning with nonseparable toroidal pulses","authors":"Ren Wang, Pan-Yi Bao, Xiaoyu Feng, Junpu Wu, Bing-Zhong Wang, Yijie Shen","doi":"10.1038/s42005-024-01850-z","DOIUrl":"10.1038/s42005-024-01850-z","url":null,"abstract":"The fundamental principle of satellite/node-based positioning involves triangulating the receiver’s coordinates through the intersection of spatial distances. Advancements in hybrid wireless networks have yielded high-precision positioning at decimeter-level (wavelength-level), approaching the resolution limits in free space. Here we present a 3D super-resolution positioning paradigm in free space by utilizing a kind of topologically structured pulses, toroidal electromagnetic pulses. We demonstrate that the space-time nonseparability and skyrmion topology inherent in toroidal pulses can be harnessed to achieve freespace microwave 3D positioning with super-resolution accuracy, reaching the centimeter level, using a single emitting antenna. This work opens up avenues for exploring the potential applications of topological electromagnetic pulses including but not limited to positioning, imaging and sensing technologies. This paper presents a positioning paradigm in free space by utilizing toroidal electromagnetic pulses. The space-time nonseparability and skyrmion topology inherent in toroidal pulses are harnessed to achieve freespace microwave 3D positioning with super-resolution accuracy, reaching the centimeter level, using a single emitting antenna.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-6"},"PeriodicalIF":5.4,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01850-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142555536","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 : 2024-10-28DOI: 10.1038/s42005-024-01842-z
Zichen Li, Bofeng Zhu, Ying Li, Yihao Yang, Yidong Chong, Qi Jie Wang, Hongsheng Chen, Song Han
Beam shaping and polarization manipulation are of great importance for the design of microcavity lasers. Recently, topological photonic cavities have emerged as excellent platforms for surface-emitting lasers. In this class of lasers, beam engineering has not thus far been extensively studied. Here, we demonstrate how to achieve an intrinsic lateral shift of the beam emitted by a topological laser. This is achieved by designing a Kekulé-modulated topological bulk cavity, in which the continuous Kekulé modulation partially lifts a set of fourfold-degenerate Dirac cones into two twofold degeneracies. The resulting photonic cavity supports a range of interesting beam emission profiles, including vector beams with polarization winding, and laterally-shifted linearly-polarized Gaussian beams. It is possible to achieve lateral beam shifts in opposite directions and orthogonal polarizations for the degenerate photonic p-/d-orbitals, a feature that may be useful for photonic sensing applications. Topological phenomena in photonics have been found of great importance in realizing advanced semiconductor laser. Here the authors demonstrate the manipulation of the light emission profiles from a Kekulé-modulated topological bulk cavity in a topological-protection manner, where the achieved lateral beam shifts in light polarizations could be useful for the laser design and photonic sensing applications.
{"title":"Kekulé-modulated topological bulk cavity for intrinsic lateral beam shifting of high-purity linear-polarized light emission","authors":"Zichen Li, Bofeng Zhu, Ying Li, Yihao Yang, Yidong Chong, Qi Jie Wang, Hongsheng Chen, Song Han","doi":"10.1038/s42005-024-01842-z","DOIUrl":"10.1038/s42005-024-01842-z","url":null,"abstract":"Beam shaping and polarization manipulation are of great importance for the design of microcavity lasers. Recently, topological photonic cavities have emerged as excellent platforms for surface-emitting lasers. In this class of lasers, beam engineering has not thus far been extensively studied. Here, we demonstrate how to achieve an intrinsic lateral shift of the beam emitted by a topological laser. This is achieved by designing a Kekulé-modulated topological bulk cavity, in which the continuous Kekulé modulation partially lifts a set of fourfold-degenerate Dirac cones into two twofold degeneracies. The resulting photonic cavity supports a range of interesting beam emission profiles, including vector beams with polarization winding, and laterally-shifted linearly-polarized Gaussian beams. It is possible to achieve lateral beam shifts in opposite directions and orthogonal polarizations for the degenerate photonic p-/d-orbitals, a feature that may be useful for photonic sensing applications. Topological phenomena in photonics have been found of great importance in realizing advanced semiconductor laser. Here the authors demonstrate the manipulation of the light emission profiles from a Kekulé-modulated topological bulk cavity in a topological-protection manner, where the achieved lateral beam shifts in light polarizations could be useful for the laser design and photonic sensing applications.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-6"},"PeriodicalIF":5.4,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01842-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525745","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 : 2024-10-28DOI: 10.1038/s42005-024-01836-x
Spencer Walker, Alexandra S. Landsman
This study delves into the relatively uncharted territory of Above Threshold Ionization in atoms, triggered by intense X-ray radiation fields. At these frequencies, the energy of a single photon far exceeds the ionization potential of valence electrons in atoms and molecules. The conditions we examine are similar to those achievable with current or future free-electron laser facilities. Under such high-energy scenarios, the onset of strong field ionization requires a shift away from the traditional quasi-classical approach. Here, we present an analytical model to characterize how the field-free ionization potential, ponderomotive energy, and photon energy govern the transition to this regime, all accounted for by means of the Keldysh and Reiss parameters. We show that both of these parameters are needed to capture the onset of strong-field behavior due to both bound state and continuum state properties. At higher X-ray intensities, we find that ionization rates deviate from the linear intensity scaling expected from lowest order perturbative processes, corresponding to channel closure and higher-order photon absorption processes. This study explores Above Threshold Ionization in atoms induced by intense X-ray radiation fields, where photon energy surpasses the ionization potential of valence electrons. The authors demonstrate that both the Keldysh and Reiss parameters are essential to capture the onset of strong-field behavior, revealing deviations from weak-field intensity scaling at higher X-ray intensities.
这项研究深入探讨了由强 X 射线辐射场引发的原子阈值以上电离这一相对未知的领域。在这些频率下，单个光子的能量远远超过了原子和分子中价电子的电离势。我们所研究的条件与当前或未来的自由电子激光设备所能达到的条件类似。在这种高能情况下，强场电离的发生需要摆脱传统的准经典方法。在此，我们提出了一个分析模型，以描述无场电离势、思索动能和光子能量如何支配向这一机制的过渡，所有这些都通过凯尔迪什参数和雷斯参数来说明。我们发现，由于束缚态和连续态的特性，需要这两个参数来捕捉强场行为的发生。在更高的 X 射线强度下，我们发现电离率偏离了最低阶扰动过程所预期的线性强度比例，这与通道关闭和高阶光子吸收过程相对应。这项研究探讨了强 X 射线辐射场诱导的原子阈值以上电离，在这种情况下，光子能量超过了价电子的电离势。作者证明了凯尔迪什参数和雷斯参数对于捕捉强场行为的发生至关重要，揭示了在较高 X 射线强度下与弱场强度缩放的偏差。
{"title":"Above-threshold ionization with X-ray free-electron lasers","authors":"Spencer Walker, Alexandra S. Landsman","doi":"10.1038/s42005-024-01836-x","DOIUrl":"10.1038/s42005-024-01836-x","url":null,"abstract":"This study delves into the relatively uncharted territory of Above Threshold Ionization in atoms, triggered by intense X-ray radiation fields. At these frequencies, the energy of a single photon far exceeds the ionization potential of valence electrons in atoms and molecules. The conditions we examine are similar to those achievable with current or future free-electron laser facilities. Under such high-energy scenarios, the onset of strong field ionization requires a shift away from the traditional quasi-classical approach. Here, we present an analytical model to characterize how the field-free ionization potential, ponderomotive energy, and photon energy govern the transition to this regime, all accounted for by means of the Keldysh and Reiss parameters. We show that both of these parameters are needed to capture the onset of strong-field behavior due to both bound state and continuum state properties. At higher X-ray intensities, we find that ionization rates deviate from the linear intensity scaling expected from lowest order perturbative processes, corresponding to channel closure and higher-order photon absorption processes. This study explores Above Threshold Ionization in atoms induced by intense X-ray radiation fields, where photon energy surpasses the ionization potential of valence electrons. The authors demonstrate that both the Keldysh and Reiss parameters are essential to capture the onset of strong-field behavior, revealing deviations from weak-field intensity scaling at higher X-ray intensities.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-16"},"PeriodicalIF":5.4,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01836-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525697","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 : 2024-10-28DOI: 10.1038/s42005-024-01825-0
Pranava K. Sivakumar, Mostafa T. Ahari, Jae-Keun Kim, Yufeng Wu, Anvesh Dixit, George J. de Coster, Avanindra K. Pandeya, Matthew J. Gilbert, Stuart S. P. Parkin
Superconducting diode effects have recently attracted much attention for their potential applications in superconducting logic circuits. Several pathways have been proposed to give rise to non-reciprocal critical currents in various superconductors and Josephson junctions. In this work, we establish the presence of a large Josephson diode effect in a type-II Dirac semimetal 1T-PtTe2 facilitated by its helical spin-momentum locking and distinguish it from extrinsic geometric effects. The magnitude of the Josephson diode effect is shown to be directly correlated to the large second-harmonic component of the supercurrent. We denote such junctions, where the relative phase between the two harmonics can be tuned by a magnetic field, as ‘tunable second order φ0-junctions’. The direct correspondence between the second harmonic supercurrents and the diode effect in 1T-PtTe2 junctions at relatively low magnetic fields makes it an ideal platform to study the Josephson diode effect and Cooper quartet transport in Josephson junctions. This work reports on the observation of a large Josephson diode effect in a type-II Dirac semimetal 1T-PtTe2. The magnitude of the Josephson diode effect is found to be related to an asymmetry of the critical supercurrent which is modeled as a phase shift between the first and second harmonic terms of the current-phase relationship and can be tuned by an external magnetic field.
超导二极管效应最近因其在超导逻辑电路中的潜在应用而备受关注。在各种超导体和约瑟夫森结中，已经提出了几种产生非互易临界电流的途径。在这项研究中，我们证实了在 II 型狄拉克半金属 1T-PtTe2 中存在由其螺旋自旋动量锁定促进的巨大约瑟夫森二极管效应，并将其与外在几何效应区分开来。约瑟夫森二极管效应的大小与超电流的大二次谐波分量直接相关。我们将这样的结称为 "可调谐二阶φ0 结"，其中两个谐波之间的相对相位可通过磁场进行调谐。在相对较低的磁场下，1T-PtTe2 结中的二次谐波超电流与二极管效应之间的直接对应关系，使其成为研究约瑟夫森二极管效应和约瑟夫森结中库珀四元组输运的理想平台。这项研究报告了在 II 型狄拉克半金属 1T-PtTe2 中观察到的巨大约瑟夫森二极管效应。研究发现，约瑟夫森二极管效应的大小与临界超电流的不对称有关，而临界超电流被模拟为电流相位关系中一次谐波项和二次谐波项之间的相移，并可通过外部磁场进行调节。
{"title":"Long-range phase coherence and tunable second order φ0-Josephson effect in a Dirac semimetal 1T-PtTe2","authors":"Pranava K. Sivakumar, Mostafa T. Ahari, Jae-Keun Kim, Yufeng Wu, Anvesh Dixit, George J. de Coster, Avanindra K. Pandeya, Matthew J. Gilbert, Stuart S. P. Parkin","doi":"10.1038/s42005-024-01825-0","DOIUrl":"10.1038/s42005-024-01825-0","url":null,"abstract":"Superconducting diode effects have recently attracted much attention for their potential applications in superconducting logic circuits. Several pathways have been proposed to give rise to non-reciprocal critical currents in various superconductors and Josephson junctions. In this work, we establish the presence of a large Josephson diode effect in a type-II Dirac semimetal 1T-PtTe2 facilitated by its helical spin-momentum locking and distinguish it from extrinsic geometric effects. The magnitude of the Josephson diode effect is shown to be directly correlated to the large second-harmonic component of the supercurrent. We denote such junctions, where the relative phase between the two harmonics can be tuned by a magnetic field, as ‘tunable second order φ0-junctions’. The direct correspondence between the second harmonic supercurrents and the diode effect in 1T-PtTe2 junctions at relatively low magnetic fields makes it an ideal platform to study the Josephson diode effect and Cooper quartet transport in Josephson junctions. This work reports on the observation of a large Josephson diode effect in a type-II Dirac semimetal 1T-PtTe2. The magnitude of the Josephson diode effect is found to be related to an asymmetry of the critical supercurrent which is modeled as a phase shift between the first and second harmonic terms of the current-phase relationship and can be tuned by an external magnetic field.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-12"},"PeriodicalIF":5.4,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01825-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525708","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}
Quantum networks typically comprise quantum channels, repeaters, and end nodes. Remote state preparation (RSP) allows one end node to prepare the states of the other end nodes remotely. While quantum discord has recently been recognized as necessary for RSP, it does not guarantee the practical implementation of RSP in quantum networks surpasses any classical method. Herein, we theoretically introduce and experimentally study a quantum resource that we call the RSP capability. This resource validates all the static and dynamic elements required to enable genuine quantum networks where the RSP’s implementation can outperform any classical emulation of entanglement- and qubit-unitaries-free strategies, including the static resources of Einstein-Podolsky-Rosen pairs and the dynamic resources of quantum channels and repeaters. Our experiment measures the RSP capability to demonstrate the transition between classical and nonclassical RSP depending on the photon-pair qualities. It shows that quantum discord does not confirm a nonclassical RSP, but the RSP capability does. These results help reveal the quantum advantages that emerge when networking RSP is in play. The authors introduce and experimentally study a quantum resource called the remote state preparation capability. This resource validates all static and dynamic elements required to enable quantum networks where the implementation of remote state preparation can outperform any classical emulation of entanglement- and qubit-unitaries-free strategies.
{"title":"Preparing remote states for genuine quantum networks","authors":"Shih-Hsuan Chen, Chan Hsu, Yu-Chien Kao, Bing-Yuan Lee, Yuan-Sung Liu, Yueh-Nan Chen, Che-Ming Li","doi":"10.1038/s42005-024-01844-x","DOIUrl":"10.1038/s42005-024-01844-x","url":null,"abstract":"Quantum networks typically comprise quantum channels, repeaters, and end nodes. Remote state preparation (RSP) allows one end node to prepare the states of the other end nodes remotely. While quantum discord has recently been recognized as necessary for RSP, it does not guarantee the practical implementation of RSP in quantum networks surpasses any classical method. Herein, we theoretically introduce and experimentally study a quantum resource that we call the RSP capability. This resource validates all the static and dynamic elements required to enable genuine quantum networks where the RSP’s implementation can outperform any classical emulation of entanglement- and qubit-unitaries-free strategies, including the static resources of Einstein-Podolsky-Rosen pairs and the dynamic resources of quantum channels and repeaters. Our experiment measures the RSP capability to demonstrate the transition between classical and nonclassical RSP depending on the photon-pair qualities. It shows that quantum discord does not confirm a nonclassical RSP, but the RSP capability does. These results help reveal the quantum advantages that emerge when networking RSP is in play. The authors introduce and experimentally study a quantum resource called the remote state preparation capability. This resource validates all static and dynamic elements required to enable quantum networks where the implementation of remote state preparation can outperform any classical emulation of entanglement- and qubit-unitaries-free strategies.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01844-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525719","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 : 2024-10-26DOI: 10.1038/s42005-024-01840-1
Cheng-Lin Lv, Zhong-Yi Li, Shi-Da Wang, Bo Li
Tissue interfaces are essential for development and their disruption often leads to diseases such as tumor invasion. Here, we combine experiments, theoretical modeling, and numerical simulations to quantify the morphodynamics of interface in a biphasic system composed of Madin Darby canine kidney (MDCK) and mouse myoblast (C2C12) cells. We show that cellular activity regulates the interface morphodynamics and drives wave propagation along the interface. Based on the dispersion relationship, we identify that the wave dynamics results from the activity-mediated instability of the interface and coherent flow. It is found that the topological defects accumulate around and destabilize the interface and +1/2 topological defects are more likely to aggregate in MDCK cell clusters. A biphasic active nematic theory is employed to reproduce our experimental observations and decipher the underlying mechanisms. These findings provide physical insights into the interfacial evolution that could be implicated in tissue morphogenesis and tumor invasion. Interfaces are ubiquitous in living systems and play pivotal roles in physiological and pathological processes. The authors combine experiments and numerical simulations to investigate morphodynamics of the interface between dissimilar cell aggregations.
{"title":"Morphodynamics of interface between dissimilar cell aggregations","authors":"Cheng-Lin Lv, Zhong-Yi Li, Shi-Da Wang, Bo Li","doi":"10.1038/s42005-024-01840-1","DOIUrl":"10.1038/s42005-024-01840-1","url":null,"abstract":"Tissue interfaces are essential for development and their disruption often leads to diseases such as tumor invasion. Here, we combine experiments, theoretical modeling, and numerical simulations to quantify the morphodynamics of interface in a biphasic system composed of Madin Darby canine kidney (MDCK) and mouse myoblast (C2C12) cells. We show that cellular activity regulates the interface morphodynamics and drives wave propagation along the interface. Based on the dispersion relationship, we identify that the wave dynamics results from the activity-mediated instability of the interface and coherent flow. It is found that the topological defects accumulate around and destabilize the interface and +1/2 topological defects are more likely to aggregate in MDCK cell clusters. A biphasic active nematic theory is employed to reproduce our experimental observations and decipher the underlying mechanisms. These findings provide physical insights into the interfacial evolution that could be implicated in tissue morphogenesis and tumor invasion. Interfaces are ubiquitous in living systems and play pivotal roles in physiological and pathological processes. The authors combine experiments and numerical simulations to investigate morphodynamics of the interface between dissimilar cell aggregations.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-11"},"PeriodicalIF":5.4,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01840-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525742","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 : 2024-10-26DOI: 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}
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