Pub Date : 2024-12-23DOI: 10.1038/s42005-024-01915-z
Junsheng Hou, Dongyu Li, Lei Huang, Li Ma, Xiong Zhao, Jinjia Wei, Nanjing Hao
Contactless acoustics provide a unique, flexible active means for phase-change heat transfer enhancement. However, the ultrasonic transducers used for conventional acoustic enhancement are bulky and unfavorable for integration, and the heat accumulation under high power is not conducive to long-term operation, with limited enhancement in the critical heat flux (CHF). Herein, an acoustic-enabled low-power compact heat exchanger (ALCHE) is proposed with low energy consumption and long operation duration. Based on image processing and bubble tracking algorithm, it is found that the acoustic field accelerates bubble detachment and migration for achieving superior heat flux and larger heat transfer coefficient (HTC). 1.5 kHz acoustic field performs better heat transfer performance due to its strong acoustic radiation force magnitude and excellent acoustic pressure field direction. The stronger acoustic radiation force from higher acoustic power promotes the heat transfer performance among different acoustic powers. Long-time stable operation of acoustic field enhanced heat transfer under high heat flux is achieved with low acoustic power. Our designed heat exchanger not only overcomes the limitation of traditional bulky transducers, but also provides insights into the acoustic-enabled flow boiling heat transfer process. Improving the cooling performance of high-power electronics in confined spaces remains a challenge. Herein, the authors propose an acoustic-enabled low-power compact heat exchanger that utilizes contactless acoustics as a flexible active means for enhancing phase change cooling.
{"title":"Electronic cooling via acoustic-enabled low-power compact heat exchanger","authors":"Junsheng Hou, Dongyu Li, Lei Huang, Li Ma, Xiong Zhao, Jinjia Wei, Nanjing Hao","doi":"10.1038/s42005-024-01915-z","DOIUrl":"10.1038/s42005-024-01915-z","url":null,"abstract":"Contactless acoustics provide a unique, flexible active means for phase-change heat transfer enhancement. However, the ultrasonic transducers used for conventional acoustic enhancement are bulky and unfavorable for integration, and the heat accumulation under high power is not conducive to long-term operation, with limited enhancement in the critical heat flux (CHF). Herein, an acoustic-enabled low-power compact heat exchanger (ALCHE) is proposed with low energy consumption and long operation duration. Based on image processing and bubble tracking algorithm, it is found that the acoustic field accelerates bubble detachment and migration for achieving superior heat flux and larger heat transfer coefficient (HTC). 1.5 kHz acoustic field performs better heat transfer performance due to its strong acoustic radiation force magnitude and excellent acoustic pressure field direction. The stronger acoustic radiation force from higher acoustic power promotes the heat transfer performance among different acoustic powers. Long-time stable operation of acoustic field enhanced heat transfer under high heat flux is achieved with low acoustic power. Our designed heat exchanger not only overcomes the limitation of traditional bulky transducers, but also provides insights into the acoustic-enabled flow boiling heat transfer process. Improving the cooling performance of high-power electronics in confined spaces remains a challenge. Herein, the authors propose an acoustic-enabled low-power compact heat exchanger that utilizes contactless acoustics as a flexible active means for enhancing phase change cooling.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01915-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142870536","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}
Anomalous Floquet topological phases are unique to periodically driven systems, lacking a static analog. Inspired by Floquet Engineering with classical electromagnetic radiation, Quantum Floquet Engineering has emerged as a promising tool to tailor the properties of quantum materials using quantum light. While the latter recovers the physics of Floquet materials in its semi-classical limit, the mapping between these two scenarios remains mysterious in many aspects. In this work, we discuss the emergence of quantum anomalous topological phases in cavity-QED materials, linking the topological phase transitions in the electron-photon spectrum with those in the 0- and π-gaps of Floquet quasienergies. Our results establish the microscopic origin of an emergent discrete time-translation symmetry in the matter sector, and link isolated c-QED materials with periodically driven ones. Finally, we discuss the bulk-edge correspondence in terms of hybrid light-matter topological invariants. Non-equilibrium systems subject to periodic driving fields, known as Floquet materials, can host unique topological phases without static counterpart. This work targets the link between Floquet physics and cavity-QED systems, and unveils the emergence of quantum anomalous phases in the latter, pointing to the important entangled light-matter dynamics.
{"title":"Quantum origin of anomalous Floquet phases in cavity-QED materials","authors":"Beatriz Pérez-González, Gloria Platero, Álvaro Gómez-León","doi":"10.1038/s42005-024-01908-y","DOIUrl":"10.1038/s42005-024-01908-y","url":null,"abstract":"Anomalous Floquet topological phases are unique to periodically driven systems, lacking a static analog. Inspired by Floquet Engineering with classical electromagnetic radiation, Quantum Floquet Engineering has emerged as a promising tool to tailor the properties of quantum materials using quantum light. While the latter recovers the physics of Floquet materials in its semi-classical limit, the mapping between these two scenarios remains mysterious in many aspects. In this work, we discuss the emergence of quantum anomalous topological phases in cavity-QED materials, linking the topological phase transitions in the electron-photon spectrum with those in the 0- and π-gaps of Floquet quasienergies. Our results establish the microscopic origin of an emergent discrete time-translation symmetry in the matter sector, and link isolated c-QED materials with periodically driven ones. Finally, we discuss the bulk-edge correspondence in terms of hybrid light-matter topological invariants. Non-equilibrium systems subject to periodic driving fields, known as Floquet materials, can host unique topological phases without static counterpart. This work targets the link between Floquet physics and cavity-QED systems, and unveils the emergence of quantum anomalous phases in the latter, pointing to the important entangled light-matter dynamics.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01908-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862433","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 : 2024-12-20DOI: 10.1038/s42005-024-01902-4
Seokyeong Lee, Dongsung T. Park, Uhjin Kim, Hwanchul Jung, Yunchul Chung, Hyoungsoon Choi, Hyung Kook Choi
Transverse magnetic focusing (TMF) is a staple technique in mesoscopic physics, used to study quasiparticles in a manner akin to mass spectrometry. However, the quantum nature of TMF has been difficult to appreciate due to several challenges in addressing the wavelike properties of the quasiparticles. Here, we report a numerical solution and experimental demonstration of the TMF wavefunction for the multichannel case, implemented using quantum point contacts in a two-dimensional electron gas. The wavefunctions could be understood as transverse modes of the emitter tracing a classical trajectory, and the geometric origins of multichannel effects were easily intuited from this simple picture. We believe our results may correspond to a near-field regime of TMF, in contrast to a far-field regime where the well-established semiclassical results are valid. Based on disorder analysis, we expect these results will apply to a wide range of realistic devices, suggesting that spatially coherent features even at the wavelength scale can be appreciated from TMF. Transverse magnetic focusing (TMF) has been widely used in mesoscopic physics, yet its quantum mechanical properties remain difficult to fully appreciate. Here, the authors present a numerical solution of TMF, analysed with channel-resolution and compared against experimental data, to expose the multichannel signatures of the TMF wavefunction.
{"title":"Channel-resolved wavefunctions of transverse magnetic focusing","authors":"Seokyeong Lee, Dongsung T. Park, Uhjin Kim, Hwanchul Jung, Yunchul Chung, Hyoungsoon Choi, Hyung Kook Choi","doi":"10.1038/s42005-024-01902-4","DOIUrl":"10.1038/s42005-024-01902-4","url":null,"abstract":"Transverse magnetic focusing (TMF) is a staple technique in mesoscopic physics, used to study quasiparticles in a manner akin to mass spectrometry. However, the quantum nature of TMF has been difficult to appreciate due to several challenges in addressing the wavelike properties of the quasiparticles. Here, we report a numerical solution and experimental demonstration of the TMF wavefunction for the multichannel case, implemented using quantum point contacts in a two-dimensional electron gas. The wavefunctions could be understood as transverse modes of the emitter tracing a classical trajectory, and the geometric origins of multichannel effects were easily intuited from this simple picture. We believe our results may correspond to a near-field regime of TMF, in contrast to a far-field regime where the well-established semiclassical results are valid. Based on disorder analysis, we expect these results will apply to a wide range of realistic devices, suggesting that spatially coherent features even at the wavelength scale can be appreciated from TMF. Transverse magnetic focusing (TMF) has been widely used in mesoscopic physics, yet its quantum mechanical properties remain difficult to fully appreciate. Here, the authors present a numerical solution of TMF, analysed with channel-resolution and compared against experimental data, to expose the multichannel signatures of the TMF wavefunction.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01902-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862467","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 : 2024-12-20DOI: 10.1038/s42005-024-01910-4
Litong Xu, Tingting Xi
Ultraviolet pulses could open up new opportunities for the study of strong-field physics and ultrafast science. However, the existing methods for generating ultraviolet pulses face difficulties in fulfilling the twofold requirements of high energy and wavelength tunability simultaneously. Here, we theoretically demonstrate the generation of high-energy and wavelength tunable ultraviolet pulses in preformed gas-plasma channels via the leaky wave emission. The output ultraviolet pulse has a tunable wavelength ranging from 91 nm to 430 nm, and an energy level up to sub-mJ. Such a high-energy tunable ultraviolet light source may provide promising opportunities for characterization of ultrafast phenomena, and also an important driving source for the generation of high-energy attosecond pulses. High-energy ultraviolet pulses serve as unique light sources for strong-field physics and ultrafast science. The authors theoretically demonstrate the generation of ultraviolet pulses with sub-mJ level energy via optical leaky wave in filamentation, where preformed gasplasma channels are used to provide adjustable dispersion conditions that enable a widely tunable wavelength range of the ultraviolet pulses.
{"title":"High-energy tunable ultraviolet pulses generated by optical leaky wave in filamentation","authors":"Litong Xu, Tingting Xi","doi":"10.1038/s42005-024-01910-4","DOIUrl":"10.1038/s42005-024-01910-4","url":null,"abstract":"Ultraviolet pulses could open up new opportunities for the study of strong-field physics and ultrafast science. However, the existing methods for generating ultraviolet pulses face difficulties in fulfilling the twofold requirements of high energy and wavelength tunability simultaneously. Here, we theoretically demonstrate the generation of high-energy and wavelength tunable ultraviolet pulses in preformed gas-plasma channels via the leaky wave emission. The output ultraviolet pulse has a tunable wavelength ranging from 91 nm to 430 nm, and an energy level up to sub-mJ. Such a high-energy tunable ultraviolet light source may provide promising opportunities for characterization of ultrafast phenomena, and also an important driving source for the generation of high-energy attosecond pulses. High-energy ultraviolet pulses serve as unique light sources for strong-field physics and ultrafast science. The authors theoretically demonstrate the generation of ultraviolet pulses with sub-mJ level energy via optical leaky wave in filamentation, where preformed gasplasma channels are used to provide adjustable dispersion conditions that enable a widely tunable wavelength range of the ultraviolet pulses.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01910-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862463","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 : 2024-12-19DOI: 10.1038/s42005-024-01904-2
Rouven Essig, Ryan Plestid, Aman Singal
Solid-state detectors with a low energy threshold have several applications, including searches of non-relativistic halo dark-matter particles with sub-GeV masses. When searching for relativistic, beyond-the-Standard-Model particles with enhanced cross sections for small energy transfers, a small detector with a low energy threshold may have better sensitivity than a larger detector with a higher energy threshold. In this paper, we calculate the low-energy ionization spectrum from high-velocity particles scattering in a dielectric material. We consider the full material response including the excitation of bulk plasmons. We generalize the energy-loss function to relativistic kinematics, and benchmark existing tools used for halo dark-matter scattering against electron energy-loss spectroscopy data. Compared to calculations commonly used in the literature, such as the Photo-Absorption-Ionization model or the free-electron model, including collective effects shifts the recoil ionization spectrum towards higher energies, typically peaking around 4–6 electron-hole pairs. We apply our results to the three benchmark examples: millicharged particles produced in a beam, neutrinos with a magnetic dipole moment produced in a reactor, and upscattered dark-matter particles. Our results show that the proper inclusion of collective effects typically enhances a detector’s sensitivity to these particles, since detector backgrounds, such as dark counts, peak at lower energies. The authors calculate the low-energy excitation cross section for relativistic feebly interacting particles scattering from silicon detectors. This enables a search for millicharged particles using data collected by the SENSEI detector and opens a new path for applications of low-threshold semi-conductor detectors to search for new physics.
{"title":"Collective excitations and low-energy ionization signatures of relativistic particles in silicon detectors","authors":"Rouven Essig, Ryan Plestid, Aman Singal","doi":"10.1038/s42005-024-01904-2","DOIUrl":"10.1038/s42005-024-01904-2","url":null,"abstract":"Solid-state detectors with a low energy threshold have several applications, including searches of non-relativistic halo dark-matter particles with sub-GeV masses. When searching for relativistic, beyond-the-Standard-Model particles with enhanced cross sections for small energy transfers, a small detector with a low energy threshold may have better sensitivity than a larger detector with a higher energy threshold. In this paper, we calculate the low-energy ionization spectrum from high-velocity particles scattering in a dielectric material. We consider the full material response including the excitation of bulk plasmons. We generalize the energy-loss function to relativistic kinematics, and benchmark existing tools used for halo dark-matter scattering against electron energy-loss spectroscopy data. Compared to calculations commonly used in the literature, such as the Photo-Absorption-Ionization model or the free-electron model, including collective effects shifts the recoil ionization spectrum towards higher energies, typically peaking around 4–6 electron-hole pairs. We apply our results to the three benchmark examples: millicharged particles produced in a beam, neutrinos with a magnetic dipole moment produced in a reactor, and upscattered dark-matter particles. Our results show that the proper inclusion of collective effects typically enhances a detector’s sensitivity to these particles, since detector backgrounds, such as dark counts, peak at lower energies. The authors calculate the low-energy excitation cross section for relativistic feebly interacting particles scattering from silicon detectors. This enables a search for millicharged particles using data collected by the SENSEI detector and opens a new path for applications of low-threshold semi-conductor detectors to search for new physics.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-11"},"PeriodicalIF":5.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01904-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862478","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}
The rapid advancement of deep learning has motivated various analog computing devices for energy-efficient non-von Neuman computing. While recent demonstrations have shown their excellent performance, particularly in the inference phase, computation of training using analog hardware is still challenging due to the complexity of training algorithms such as backpropagation. Here, we present an alternative training algorithm that combines two emerging concepts: reservoir computing (RC) and biologically inspired training. Instead of backpropagated errors, the proposed method computes the error projection using nonlinear dynamics (i.e., reservoir), which is highly suitable for physical implementation because it only requires a single passive dynamical system with a smaller number of nodes. Numerical simulation with Lyapunov analysis showed some interesting features of our proposed algorithm itself: the reservoir basically should be selected to satisfy the echo-state-property; but even chaotic dynamics can be used for the training when its time scale is below the Lyapunov time; and the performance is maximized near the edge of chaos, which is similar to standard RC framework. Furthermore, we experimentally demonstrated the training of feedforward neural networks by using an optoelectronic reservoir computer. Our approach provides an alternative solution for deep learning computation and its physical acceleration. Existing training algorithms for deep neural networks are not suitable for energy-efficient analog hardware. Here, the authors propose and experimentally demonstrate an alternative training algorithm based on reservoir computing, which improves training efficiency in optoelectronic implementations.
{"title":"Reservoir direct feedback alignment: deep learning by physical dynamics","authors":"Mitsumasa Nakajima, Yongbo Zhang, Katsuma Inoue, Yasuo Kuniyoshi, Toshikazu Hashimoto, Kohei Nakajima","doi":"10.1038/s42005-024-01895-0","DOIUrl":"10.1038/s42005-024-01895-0","url":null,"abstract":"The rapid advancement of deep learning has motivated various analog computing devices for energy-efficient non-von Neuman computing. While recent demonstrations have shown their excellent performance, particularly in the inference phase, computation of training using analog hardware is still challenging due to the complexity of training algorithms such as backpropagation. Here, we present an alternative training algorithm that combines two emerging concepts: reservoir computing (RC) and biologically inspired training. Instead of backpropagated errors, the proposed method computes the error projection using nonlinear dynamics (i.e., reservoir), which is highly suitable for physical implementation because it only requires a single passive dynamical system with a smaller number of nodes. Numerical simulation with Lyapunov analysis showed some interesting features of our proposed algorithm itself: the reservoir basically should be selected to satisfy the echo-state-property; but even chaotic dynamics can be used for the training when its time scale is below the Lyapunov time; and the performance is maximized near the edge of chaos, which is similar to standard RC framework. Furthermore, we experimentally demonstrated the training of feedforward neural networks by using an optoelectronic reservoir computer. Our approach provides an alternative solution for deep learning computation and its physical acceleration. Existing training algorithms for deep neural networks are not suitable for energy-efficient analog hardware. Here, the authors propose and experimentally demonstrate an alternative training algorithm based on reservoir computing, which improves training efficiency in optoelectronic implementations.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01895-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142845190","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 : 2024-12-19DOI: 10.1038/s42005-024-01891-4
Elmer L. Gründeman, Vincent Barbé, Andrés Martínez de Velasco, Charlaine Roth, Mathieu Collombon, Julian J. Krauth, Laura S. Dreissen, Richard Taïeb, Kjeld S. E. Eikema
Laser spectroscopy of atomic hydrogen and hydrogen-like atoms is a powerful tool for tests of fundamental physics. The 1S–2S transition of hydrogen in particular is a cornerstone for stringent Quantum Electrodynamics (QED) tests and for an accurate determination of the Rydberg constant. We report laser excitation of the 1S–2S transition in singly-ionized helium (3He+), a hydrogen-like ion with much higher sensitivity to QED than hydrogen itself. The transition requires two-photon excitation in the challenging extreme ultraviolet wavelength range, which we achieve with a tabletop coherent laser system suitable for precision spectroscopy. The transition is excited by combining an ultrafast amplified pulse at 790 nm (derived from a frequency comb laser) with its 25th harmonic at 32 nm (produced by high-harmonic generation). The results are well described by our simulations and we achieve a sizable 2S excitation fraction of 10−4 per pulse, paving the way for future precision studies. A measurement of the 1S-2S transition frequency in He+ would enable fundamental physics tests, but the required extreme ultraviolet radiation makes this a challenge. The authors observe such transition using radiation produced by high-harmonic generation of frequency comb pulses, in a manner that is compatible with future precision spectroscopy.
{"title":"Laser excitation of the 1S–2S transition in singly-ionized helium","authors":"Elmer L. Gründeman, Vincent Barbé, Andrés Martínez de Velasco, Charlaine Roth, Mathieu Collombon, Julian J. Krauth, Laura S. Dreissen, Richard Taïeb, Kjeld S. E. Eikema","doi":"10.1038/s42005-024-01891-4","DOIUrl":"10.1038/s42005-024-01891-4","url":null,"abstract":"Laser spectroscopy of atomic hydrogen and hydrogen-like atoms is a powerful tool for tests of fundamental physics. The 1S–2S transition of hydrogen in particular is a cornerstone for stringent Quantum Electrodynamics (QED) tests and for an accurate determination of the Rydberg constant. We report laser excitation of the 1S–2S transition in singly-ionized helium (3He+), a hydrogen-like ion with much higher sensitivity to QED than hydrogen itself. The transition requires two-photon excitation in the challenging extreme ultraviolet wavelength range, which we achieve with a tabletop coherent laser system suitable for precision spectroscopy. The transition is excited by combining an ultrafast amplified pulse at 790 nm (derived from a frequency comb laser) with its 25th harmonic at 32 nm (produced by high-harmonic generation). The results are well described by our simulations and we achieve a sizable 2S excitation fraction of 10−4 per pulse, paving the way for future precision studies. A measurement of the 1S-2S transition frequency in He+ would enable fundamental physics tests, but the required extreme ultraviolet radiation makes this a challenge. The authors observe such transition using radiation produced by high-harmonic generation of frequency comb pulses, in a manner that is compatible with future precision spectroscopy.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-6"},"PeriodicalIF":5.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01891-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862430","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 : 2024-12-19DOI: 10.1038/s42005-024-01885-2
Juan G. Restrepo, Clayton P. Byers, Per Sebastian Skardal
Identifying and suppressing unknown disturbances to dynamical systems is a problem with applications in many different fields. Here we present a model-free method to identify and suppress an unknown disturbance to an unknown system based only on previous observations of the system under the influence of a known forcing function. We find that, under very mild restrictions on the training function, our method is able to robustly identify and suppress a large class of unknown disturbances. We illustrate our scheme with the identification of both deterministic and stochastic unknown disturbances to an analog electric chaotic circuit and with numerical examples where a chaotic disturbance to various chaotic dynamical systems is identified and suppressed. Identifying and mitigating unknown disturbances to complex systems poses a critical challenge in a wide range of disciplines. Here, the authors use machine learning to identify unknown disturbances made to unknown systems and a methodology to suppress these disturbances to recover the undisturbed system.
{"title":"Suppressing unknown disturbances to dynamical systems using machine learning","authors":"Juan G. Restrepo, Clayton P. Byers, Per Sebastian Skardal","doi":"10.1038/s42005-024-01885-2","DOIUrl":"10.1038/s42005-024-01885-2","url":null,"abstract":"Identifying and suppressing unknown disturbances to dynamical systems is a problem with applications in many different fields. Here we present a model-free method to identify and suppress an unknown disturbance to an unknown system based only on previous observations of the system under the influence of a known forcing function. We find that, under very mild restrictions on the training function, our method is able to robustly identify and suppress a large class of unknown disturbances. We illustrate our scheme with the identification of both deterministic and stochastic unknown disturbances to an analog electric chaotic circuit and with numerical examples where a chaotic disturbance to various chaotic dynamical systems is identified and suppressed. Identifying and mitigating unknown disturbances to complex systems poses a critical challenge in a wide range of disciplines. Here, the authors use machine learning to identify unknown disturbances made to unknown systems and a methodology to suppress these disturbances to recover the undisturbed system.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01885-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142862424","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 : 2024-12-19DOI: 10.1038/s42005-024-01897-y
Shanshan Liu, Rhonald Burgos, Enze Zhang, Naizhou Wang, Xiao-Bin Qiang, Chuanzhao Li, Qihan Zhang, Z. Z. Du, Rui Zheng, Jingsheng Chen, Qing-Hua Xu, Kai Leng, Weibo Gao, Faxian Xiu, Dimitrie Culcer, Kian Ping Loh
The discovery of the nonlinear Hall effect provides an avenue for studying the interplay among symmetry, topology, and phase transitions, with potential applications in signal doubling and high-frequency rectification. However, practical applications require devices fabricated on large area thin film as well as room-temperature operation. Here, we demonstrate robust room-temperature nonlinear transverse response and microwave rectification in MnBi2Te4 films grown by molecular beam epitaxy. We observe multiple sign-reversals in the nonlinear response by tuning the chemical potential. Through theoretical analysis, we identify skew scattering and side jump, arising from extrinsic spin-orbit scattering, as the main mechanisms underlying the observed nonlinear signals. Furthermore, we demonstrate radio frequency (RF) rectification in the range of 1–8 gigahertz at 300 K. These findings not only enhance our understanding of the relationship between nonlinear response and magnetism, but also expand the potential applications as energy harvesters and detectors in high-frequency scenarios. The nonlinear Hall effect enables studies of symmetry and topology with potential in high-frequency devices, but practical applications demand room temperature operation. The authors report robust room temperature nonlinear transverse responses and microwave rectification (1–8 GHz) in MnBi2Te4 thin films, driven by extrinsic spin-orbit scattering.
{"title":"Room-temperature nonlinear transport and microwave rectification in antiferromagnetic MnBi2Te4 films","authors":"Shanshan Liu, Rhonald Burgos, Enze Zhang, Naizhou Wang, Xiao-Bin Qiang, Chuanzhao Li, Qihan Zhang, Z. Z. Du, Rui Zheng, Jingsheng Chen, Qing-Hua Xu, Kai Leng, Weibo Gao, Faxian Xiu, Dimitrie Culcer, Kian Ping Loh","doi":"10.1038/s42005-024-01897-y","DOIUrl":"10.1038/s42005-024-01897-y","url":null,"abstract":"The discovery of the nonlinear Hall effect provides an avenue for studying the interplay among symmetry, topology, and phase transitions, with potential applications in signal doubling and high-frequency rectification. However, practical applications require devices fabricated on large area thin film as well as room-temperature operation. Here, we demonstrate robust room-temperature nonlinear transverse response and microwave rectification in MnBi2Te4 films grown by molecular beam epitaxy. We observe multiple sign-reversals in the nonlinear response by tuning the chemical potential. Through theoretical analysis, we identify skew scattering and side jump, arising from extrinsic spin-orbit scattering, as the main mechanisms underlying the observed nonlinear signals. Furthermore, we demonstrate radio frequency (RF) rectification in the range of 1–8 gigahertz at 300 K. These findings not only enhance our understanding of the relationship between nonlinear response and magnetism, but also expand the potential applications as energy harvesters and detectors in high-frequency scenarios. The nonlinear Hall effect enables studies of symmetry and topology with potential in high-frequency devices, but practical applications demand room temperature operation. The authors report robust room temperature nonlinear transverse responses and microwave rectification (1–8 GHz) in MnBi2Te4 thin films, driven by extrinsic spin-orbit scattering.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01897-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142845149","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 : 2024-12-19DOI: 10.1038/s42005-024-01899-w
Keita Funayama, Kenichi Yatsugi, Hideo Iizuka
Topological artificial crystals can exhibit one-way wave-propagation along the boundary with the wave being localized perpendicular to the boundary. The control of localization of such topological wave propagation is of great importance for enhancing coupling or avoiding unwanted coupling among neighboring boundaries toward topological integrated circuits. However, the effect of the geometry of topological boundaries on localization properties is not yet fully clear. Here, we experimentally and numerically demonstrate valley-topological transport on representative valley-topological boundaries with micro-electro-mechanical systems. We show that the zigzag and bridge boundaries, which have highly efficient wave transport, exhibit frequency independent and dependent wave localization, respectively. A simple analytic model is presented to capture the different behaviors of the two boundaries observed in the experiments. Our results provide opportunities to engineer frequency responses in topological circuits including frequency selective couplers through proper selection of boundary geometries. The authors numerically and experimentally investigate the transport properties of a quantum valley-Hall effect in a micro electromechanical system. The zigzag and bridge boundaries, which have highly efficient wave transport, exhibit frequency independent and dependent wave localization, respectively.
{"title":"Quantum valley Hall effect-based topological boundaries for frequency-dependent and -independent mode energy profiles","authors":"Keita Funayama, Kenichi Yatsugi, Hideo Iizuka","doi":"10.1038/s42005-024-01899-w","DOIUrl":"10.1038/s42005-024-01899-w","url":null,"abstract":"Topological artificial crystals can exhibit one-way wave-propagation along the boundary with the wave being localized perpendicular to the boundary. The control of localization of such topological wave propagation is of great importance for enhancing coupling or avoiding unwanted coupling among neighboring boundaries toward topological integrated circuits. However, the effect of the geometry of topological boundaries on localization properties is not yet fully clear. Here, we experimentally and numerically demonstrate valley-topological transport on representative valley-topological boundaries with micro-electro-mechanical systems. We show that the zigzag and bridge boundaries, which have highly efficient wave transport, exhibit frequency independent and dependent wave localization, respectively. A simple analytic model is presented to capture the different behaviors of the two boundaries observed in the experiments. Our results provide opportunities to engineer frequency responses in topological circuits including frequency selective couplers through proper selection of boundary geometries. The authors numerically and experimentally investigate the transport properties of a quantum valley-Hall effect in a micro electromechanical system. The zigzag and bridge boundaries, which have highly efficient wave transport, exhibit frequency independent and dependent wave localization, respectively.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-7"},"PeriodicalIF":5.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01899-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142845139","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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