Pub Date : 2024-12-27DOI: 10.1038/s42005-024-01920-2
Yue Xiao, Yongxu Peng, Linfeng Chen, Chunhui Li, Zongao Song, Xin Wang, Tao Wang, Yurun Xie, Bin Zhao, Tiangang Yang
Laser cooling typically requires one or more repump lasers to clear dark states, which complicates experimental setups, especially for systems with multiple repumping frequencies. Here, we demonstrate cooling of Be+ ions using a single laser beam, enabled by micromotion-induced one-dimensional heating. By manipulating the displacement of Be+ ions from the trap’s nodal line, we precisely control the ion micromotion velocity, eliminating the necessity of a 1.25 GHz offset repump laser while keeping ions cold in the direction perpendicular to the micromotion. We use two equivalent schemes, cooling laser detuning and ion trajectory imaging to measure the speed of the Be+ ions, with results accurately reproduced by molecular dynamics simulations based on a machine learned time-dependent electric field inside the trap. This work provides a robust method to control micromotion velocity of ions and demonstrates the potential of micromotion-assisted laser cooling to simplify setups for systems requiring multiple repumping frequencies. Reducing the number of lasers in laser cooling experiments is beneficial for simplifying systems requiring multiple repumping frequencies. This work demonstrates micromotion-assisted cooling of Be+ ions with a single laser, eliminating the need for a 1.25 GHz offset repump laser, with results rigorously validated through molecular dynamics simulations.
{"title":"Two-dimensional cooling without repump laser beams through ion motional heating","authors":"Yue Xiao, Yongxu Peng, Linfeng Chen, Chunhui Li, Zongao Song, Xin Wang, Tao Wang, Yurun Xie, Bin Zhao, Tiangang Yang","doi":"10.1038/s42005-024-01920-2","DOIUrl":"10.1038/s42005-024-01920-2","url":null,"abstract":"Laser cooling typically requires one or more repump lasers to clear dark states, which complicates experimental setups, especially for systems with multiple repumping frequencies. Here, we demonstrate cooling of Be+ ions using a single laser beam, enabled by micromotion-induced one-dimensional heating. By manipulating the displacement of Be+ ions from the trap’s nodal line, we precisely control the ion micromotion velocity, eliminating the necessity of a 1.25 GHz offset repump laser while keeping ions cold in the direction perpendicular to the micromotion. We use two equivalent schemes, cooling laser detuning and ion trajectory imaging to measure the speed of the Be+ ions, with results accurately reproduced by molecular dynamics simulations based on a machine learned time-dependent electric field inside the trap. This work provides a robust method to control micromotion velocity of ions and demonstrates the potential of micromotion-assisted laser cooling to simplify setups for systems requiring multiple repumping frequencies. Reducing the number of lasers in laser cooling experiments is beneficial for simplifying systems requiring multiple repumping frequencies. This work demonstrates micromotion-assisted cooling of Be+ ions with a single laser, eliminating the need for a 1.25 GHz offset repump laser, with results rigorously validated through molecular dynamics simulations.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01920-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890099","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 : 2024-12-26DOI: 10.1038/s42005-024-01896-z
The DarkSide-20k Collaboration
The dual-phase liquid argon time projection chamber is presently one of the leading technologies to search for dark matter particles with masses below 10 GeV c−2. This was demonstrated by the DarkSide-50 experiment with approximately 50 kg of low-radioactivity liquid argon as target material. The next generation experiment DarkSide-20k, currently under construction, will use 1,000 times more argon and is expected to start operation in 2027. Based on the DarkSide-50 experience, here we assess the DarkSide-20k sensitivity to models predicting light dark matter particles, including Weakly Interacting Massive Particles (WIMPs) and sub-GeV c−2 particles interacting with electrons in argon atoms. With one year of data, a sensitivity improvement to dark matter interaction cross-sections by at least one order of magnitude with respect to DarkSide-50 is expected for all these models. A sensitivity to WIMP–nucleon interaction cross-sections below 1 × 10−42 cm2 is achievable for WIMP masses above 800 MeV c−2. With 10 years exposure, the neutrino fog can be reached for WIMP masses around 5 GeV c−2. The DarkSide-20k collaboration reports the sensitivity of its detector, currently under construction, to models predicting light dark matter particles. This includes Weakly Interacting Massive Particles and particles interacting with bound electrons of argon atoms.
{"title":"DarkSide-20k sensitivity to light dark matter particles","authors":"The DarkSide-20k Collaboration","doi":"10.1038/s42005-024-01896-z","DOIUrl":"10.1038/s42005-024-01896-z","url":null,"abstract":"The dual-phase liquid argon time projection chamber is presently one of the leading technologies to search for dark matter particles with masses below 10 GeV c−2. This was demonstrated by the DarkSide-50 experiment with approximately 50 kg of low-radioactivity liquid argon as target material. The next generation experiment DarkSide-20k, currently under construction, will use 1,000 times more argon and is expected to start operation in 2027. Based on the DarkSide-50 experience, here we assess the DarkSide-20k sensitivity to models predicting light dark matter particles, including Weakly Interacting Massive Particles (WIMPs) and sub-GeV c−2 particles interacting with electrons in argon atoms. With one year of data, a sensitivity improvement to dark matter interaction cross-sections by at least one order of magnitude with respect to DarkSide-50 is expected for all these models. A sensitivity to WIMP–nucleon interaction cross-sections below 1 × 10−42 cm2 is achievable for WIMP masses above 800 MeV c−2. With 10 years exposure, the neutrino fog can be reached for WIMP masses around 5 GeV c−2. The DarkSide-20k collaboration reports the sensitivity of its detector, currently under construction, to models predicting light dark matter particles. This includes Weakly Interacting Massive Particles and particles interacting with bound electrons of argon atoms.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01896-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890026","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 : 2024-12-24DOI: 10.1038/s42005-024-01909-x
Riccardo Gallotti, Davide Maniscalco, Marc Barthelemy, Manlio De Domenico
The description of human mobility is at the core of many fundamental applications ranging from urbanism and transportation to epidemics containment. Data about human movements, once scarce, is now widely available thanks to new sources such as phone call detail records, GPS devices, or Smartphone apps. Nevertheless, it is still common to rely on a single dataset by implicitly assuming that the statistical properties observed are robust regardless of data gathering and processing techniques. Here, we test this assumption on a broad scale by comparing human mobility datasets obtained from 7 different data-sources, tracing 500+ millions individuals in 145 countries. We report wide quantifiable differences in the resulting mobility networks and in the displacement distribution. These variations impact processes taking place on these networks like epidemic spreading. Our results point to the need for disclosing the data processing and, overall, to follow good practices to ensure robust and reproducible results. Human mobility data is crucial for many applications, but researchers often rely on single datasets assuming universal validity. Comparing 7 diverse sources across 145 countries, we find significant differences in mobility patterns and networks, impacting applications like epidemic modeling and emphasizing the need for transparent data processing.
{"title":"Distorted insights from human mobility data","authors":"Riccardo Gallotti, Davide Maniscalco, Marc Barthelemy, Manlio De Domenico","doi":"10.1038/s42005-024-01909-x","DOIUrl":"10.1038/s42005-024-01909-x","url":null,"abstract":"The description of human mobility is at the core of many fundamental applications ranging from urbanism and transportation to epidemics containment. Data about human movements, once scarce, is now widely available thanks to new sources such as phone call detail records, GPS devices, or Smartphone apps. Nevertheless, it is still common to rely on a single dataset by implicitly assuming that the statistical properties observed are robust regardless of data gathering and processing techniques. Here, we test this assumption on a broad scale by comparing human mobility datasets obtained from 7 different data-sources, tracing 500+ millions individuals in 145 countries. We report wide quantifiable differences in the resulting mobility networks and in the displacement distribution. These variations impact processes taking place on these networks like epidemic spreading. Our results point to the need for disclosing the data processing and, overall, to follow good practices to ensure robust and reproducible results. Human mobility data is crucial for many applications, but researchers often rely on single datasets assuming universal validity. Comparing 7 diverse sources across 145 countries, we find significant differences in mobility patterns and networks, impacting applications like epidemic modeling and emphasizing the need for transparent data processing.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01909-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142880567","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 : 2024-12-23DOI: 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}
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}
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}
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