Pub Date : 2024-09-17DOI: 10.1038/s42005-024-01795-3
Abhinav Naga, Michael Rennick, Lukas Hauer, William S. Y. Wong, Azadeh Sharifi-Aghili, Doris Vollmer, Halim Kusumaatmaja
Drops are exceptionally mobile on lubricant-infused surfaces, yet they exhibit fundamentally different dynamics than on traditional superhydrophobic surfaces due to the formation of a wetting ridge around the drop. Despite the importance of the wetting ridge in controlling drop motion, it is unclear how it dissipates energy and changes shape during motion. Here, we use lattice Boltzmann simulations and confocal microscopy to image how the wetting ridge evolves with speed, and construct heatmaps to visualize where energy is dissipated on flat and rough lubricated surfaces. As speed increases, the wetting ridge height decreases according to a power law, and an asymmetry develops between the front and rear sides. Most of the dissipation in the lubricant ( >75%) occurs directly in front and behind the drop. The geometry of the underlying solid surface hardly affects the dissipation mechanism, implying that future designs should focus on optimizing the surface geometry to maximize lubricant retention. Droplet dynamics on lubricated surfaces differ fundamentally from those on dry surfaces due to the formation of a wetting ridge around the droplet. By combining confocal microscopy and lattice Boltzmann simulations, the authors elucidate how the wetting ridge geometry evolves with speed and create heatmaps to reveal where energy is dissipated during motion.
{"title":"Direct visualization of viscous dissipation and wetting ridge geometry on lubricant-infused surfaces","authors":"Abhinav Naga, Michael Rennick, Lukas Hauer, William S. Y. Wong, Azadeh Sharifi-Aghili, Doris Vollmer, Halim Kusumaatmaja","doi":"10.1038/s42005-024-01795-3","DOIUrl":"10.1038/s42005-024-01795-3","url":null,"abstract":"Drops are exceptionally mobile on lubricant-infused surfaces, yet they exhibit fundamentally different dynamics than on traditional superhydrophobic surfaces due to the formation of a wetting ridge around the drop. Despite the importance of the wetting ridge in controlling drop motion, it is unclear how it dissipates energy and changes shape during motion. Here, we use lattice Boltzmann simulations and confocal microscopy to image how the wetting ridge evolves with speed, and construct heatmaps to visualize where energy is dissipated on flat and rough lubricated surfaces. As speed increases, the wetting ridge height decreases according to a power law, and an asymmetry develops between the front and rear sides. Most of the dissipation in the lubricant ( >75%) occurs directly in front and behind the drop. The geometry of the underlying solid surface hardly affects the dissipation mechanism, implying that future designs should focus on optimizing the surface geometry to maximize lubricant retention. Droplet dynamics on lubricated surfaces differ fundamentally from those on dry surfaces due to the formation of a wetting ridge around the droplet. By combining confocal microscopy and lattice Boltzmann simulations, the authors elucidate how the wetting ridge geometry evolves with speed and create heatmaps to reveal where energy is dissipated during motion.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-12"},"PeriodicalIF":5.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01795-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142251900","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 : 2024-09-17DOI: 10.1038/s42005-024-01797-1
Xiang Li, Elena Bykova, Denis Vasiukov, Georgios Aprilis, Stella Chariton, Valerio Cerantola, Maxim Bykov, Susanne Müller, Anna Pakhomova, Fariia I. Akbar, Elena Mukhina, Innokenty Kantor, Konstantin Glazyrin, Davide Comboni, Aleksandr I. Chumakov, Catherine McCammon, Leonid Dubrovinsky, Carmen Sanchez-Valle, Ilya Kupenko
Fe1-xO, although chemically simple, possesses a complex structural and magnetic phase diagram. The crystal structures of Fe1-xO and its magnetic properties at extreme conditions are still a matter of debate. Here, we performed a systematic investigation on Fe0.94O up to 94 GPa and 1700 K using synchrotron X-ray diffraction and synchrotron Mössbauer source spectroscopy. We observe a transition of Fe0.94O to the monoclinic phases above 40 GPa and at high temperatures and use the group theory analysis of the observed phases to discuss their properties and their relation to the ambient pressure phases. The Mössbauer spectra of the rhombohedral and the room temperature monoclinic phase contain a component attributed to Fe2.5+, caused by the electron exchange between the Fe3+ defect and neighboring Fe2+ atoms. Our results present a structural and magnetic transitional pressure-temperature diagram of Fe1-xO and show the complex physicochemical properties of simple Fe1-xO binary oxide under extreme conditions. This work concerns a systematic study of Fe1-xO employing complementary methods of powder and single-crystal X-ray diffraction and synchrotron Mössbauer source spectroscopy up to 94 GPa and 1700 K. It presents a structural and magnetic transitional pressure-temperature diagram of Fe1-xO and demonstrates the complex physicochemical properties of simple Fe1-xO binary oxide under extreme conditions.
{"title":"Monoclinic distortion and magnetic transitions in FeO under pressure and temperature","authors":"Xiang Li, Elena Bykova, Denis Vasiukov, Georgios Aprilis, Stella Chariton, Valerio Cerantola, Maxim Bykov, Susanne Müller, Anna Pakhomova, Fariia I. Akbar, Elena Mukhina, Innokenty Kantor, Konstantin Glazyrin, Davide Comboni, Aleksandr I. Chumakov, Catherine McCammon, Leonid Dubrovinsky, Carmen Sanchez-Valle, Ilya Kupenko","doi":"10.1038/s42005-024-01797-1","DOIUrl":"10.1038/s42005-024-01797-1","url":null,"abstract":"Fe1-xO, although chemically simple, possesses a complex structural and magnetic phase diagram. The crystal structures of Fe1-xO and its magnetic properties at extreme conditions are still a matter of debate. Here, we performed a systematic investigation on Fe0.94O up to 94 GPa and 1700 K using synchrotron X-ray diffraction and synchrotron Mössbauer source spectroscopy. We observe a transition of Fe0.94O to the monoclinic phases above 40 GPa and at high temperatures and use the group theory analysis of the observed phases to discuss their properties and their relation to the ambient pressure phases. The Mössbauer spectra of the rhombohedral and the room temperature monoclinic phase contain a component attributed to Fe2.5+, caused by the electron exchange between the Fe3+ defect and neighboring Fe2+ atoms. Our results present a structural and magnetic transitional pressure-temperature diagram of Fe1-xO and show the complex physicochemical properties of simple Fe1-xO binary oxide under extreme conditions. This work concerns a systematic study of Fe1-xO employing complementary methods of powder and single-crystal X-ray diffraction and synchrotron Mössbauer source spectroscopy up to 94 GPa and 1700 K. It presents a structural and magnetic transitional pressure-temperature diagram of Fe1-xO and demonstrates the complex physicochemical properties of simple Fe1-xO binary oxide under extreme conditions.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-11"},"PeriodicalIF":5.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01797-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142251902","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 : 2024-09-13DOI: 10.1038/s42005-024-01794-4
Andrew D. Ross, Diptarka Hait, Valeriu Scutelnic, Daniel M. Neumark, Martin Head-Gordon, Stephen R. Leone
X-ray Transient Absorption Spectroscopy (XTAS) is a powerful probe for ultrafast molecular dynamics. The evolution of XTAS signal is controlled by the shapes of potential energy surfaces of the associated core-excited states, which are difficult to directly measure. Here, we study the vibrational dynamics of Raman activated CCl4 with XTAS targeting the C 1s and Cl 2p electrons. The totally symmetric stretching mode leads to concerted elongation or contraction in bond lengths, which in turn induce an experimentally measurable red or blue shift in the X-ray absorption energies associated with inner-shell electron excitations to the valence antibonding levels. The ratios between slopes of different core-excited potential energy surfaces (CEPESs) thereby extracted agree very well with Restricted Open-Shell Kohn-Sham calculations. The other, asymmetric, modes do not measurably contribute to the XTAS signal. The results highlight the ability of XTAS to reveal coherent nuclear dynamics involving < 0.01 Å atomic displacements and also provide direct measurement of forces on CEPESs. The evolution of X-ray transient absorption signal in studies of ultrafast molecular dynamics is controlled by the shapes of potential energy surfaces of the associated core-excited states. The authors use experiment and theory to measure the slopes of potential energy surfaces for excitations out of the C 1s and Cl 2p shells to valence antibonding orbitals in CCl4
X 射线瞬态吸收光谱（XTAS）是超快分子动力学的强大探针。XTAS 信号的演变受相关核心激发态势能面形状的控制，而这些势能面形状很难直接测量。在这里，我们利用针对 C 1s 和 Cl 2p 电子的 XTAS 研究了拉曼激活的 CCl4 的振动动力学。完全对称的伸展模式会导致键长的协同伸长或收缩，这反过来又会引起与内壳电子激发到价反键水平相关的 X 射线吸收能量发生可测量的红移或蓝移。由此提取的不同核激发势能面（CEPES）斜率之间的比率与限制性开壳 Kohn-Sham 计算结果非常吻合。其他不对称模式对 XTAS 信号的贡献并不明显。这些结果突显了 XTAS 揭示涉及 0.01 Å 原子位移的相干核动力学的能力，同时也提供了对 CEPES 受力的直接测量。在超快分子动力学研究中，X 射线瞬态吸收信号的演变受相关核激发态势能面形状的控制。作者利用实验和理论测量了从 C 1s 和 Cl 2p 壳激发到 CCl4 中价反键轨道的势能面斜率。
{"title":"Measurement of coherent vibrational dynamics with X-ray Transient Absorption Spectroscopy simultaneously at the Carbon K- and Chlorine L2,3- edges","authors":"Andrew D. Ross, Diptarka Hait, Valeriu Scutelnic, Daniel M. Neumark, Martin Head-Gordon, Stephen R. Leone","doi":"10.1038/s42005-024-01794-4","DOIUrl":"10.1038/s42005-024-01794-4","url":null,"abstract":"X-ray Transient Absorption Spectroscopy (XTAS) is a powerful probe for ultrafast molecular dynamics. The evolution of XTAS signal is controlled by the shapes of potential energy surfaces of the associated core-excited states, which are difficult to directly measure. Here, we study the vibrational dynamics of Raman activated CCl4 with XTAS targeting the C 1s and Cl 2p electrons. The totally symmetric stretching mode leads to concerted elongation or contraction in bond lengths, which in turn induce an experimentally measurable red or blue shift in the X-ray absorption energies associated with inner-shell electron excitations to the valence antibonding levels. The ratios between slopes of different core-excited potential energy surfaces (CEPESs) thereby extracted agree very well with Restricted Open-Shell Kohn-Sham calculations. The other, asymmetric, modes do not measurably contribute to the XTAS signal. The results highlight the ability of XTAS to reveal coherent nuclear dynamics involving < 0.01 Å atomic displacements and also provide direct measurement of forces on CEPESs. The evolution of X-ray transient absorption signal in studies of ultrafast molecular dynamics is controlled by the shapes of potential energy surfaces of the associated core-excited states. The authors use experiment and theory to measure the slopes of potential energy surfaces for excitations out of the C 1s and Cl 2p shells to valence antibonding orbitals in CCl4","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01794-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233239","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 : 2024-09-10DOI: 10.1038/s42005-024-01769-5
Marcus Tamura, Hugh Morison, Alexander N. Tait, Bhavin J. Shastri
Increasingly, artificial intelligent systems look to neuromorphic photonics for its speed and its low loss, high bandwidth interconnects. Silicon photonics has shown promise to enable the creation of large scale neural networks. Here, we propose a monolithic silicon opto-electronic resonator spiking neuron. Existing designs of photonic spiking neurons have difficulty scaling due to their dependence on certain nonlinear effects, materials, and devices. The design discussed here uses optical feedback from the transmission of a continuously pumped microring PN modulator to achieve excitable dynamics. It is cascadable, capable of operating at GHz speeds, and compatible with wavelength-division multiplexing schemes for linear weighting. It is a Class 2 excitable device via a subcritical Hopf bifurcation constructed from devices commonly found in many silicon photonic chip foundries. Silicon photonics can be used to create high-speed large-scale neuromorphic systems for artificial intelligent tasks. Here, the authors discuss the design details and behavior of a resonator spiking neuron that can be fabricated in a commercial silicon photonics foundry process.
{"title":"Design of a monolithic silicon-on-insulator resonator spiking neuron","authors":"Marcus Tamura, Hugh Morison, Alexander N. Tait, Bhavin J. Shastri","doi":"10.1038/s42005-024-01769-5","DOIUrl":"10.1038/s42005-024-01769-5","url":null,"abstract":"Increasingly, artificial intelligent systems look to neuromorphic photonics for its speed and its low loss, high bandwidth interconnects. Silicon photonics has shown promise to enable the creation of large scale neural networks. Here, we propose a monolithic silicon opto-electronic resonator spiking neuron. Existing designs of photonic spiking neurons have difficulty scaling due to their dependence on certain nonlinear effects, materials, and devices. The design discussed here uses optical feedback from the transmission of a continuously pumped microring PN modulator to achieve excitable dynamics. It is cascadable, capable of operating at GHz speeds, and compatible with wavelength-division multiplexing schemes for linear weighting. It is a Class 2 excitable device via a subcritical Hopf bifurcation constructed from devices commonly found in many silicon photonic chip foundries. Silicon photonics can be used to create high-speed large-scale neuromorphic systems for artificial intelligent tasks. Here, the authors discuss the design details and behavior of a resonator spiking neuron that can be fabricated in a commercial silicon photonics foundry process.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-7"},"PeriodicalIF":5.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01769-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182131","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 : 2024-09-06DOI: 10.1038/s42005-024-01790-8
Adrian Skasberg Aasen, Andras Di Giovanni, Hannes Rotzinger, Alexey V. Ustinov, Martin Gärttner
Quantum technologies rely heavily on accurate control and reliable readout of quantum systems. Current experiments are limited by numerous sources of noise that can only be partially captured by simple analytical models and additional characterization of the noise sources is required. We test the ability of readout error mitigation to correct noise found in systems composed of quantum two-level objects (qubits). To probe the limit of such methods, we designed a beyond-classical readout error mitigation protocol based on quantum state tomography (QST), which estimates the density matrix of a quantum system, and quantum detector tomography (QDT), which characterizes the measurement procedure. By treating readout error mitigation in the context of state tomography the method becomes largely readout mode-, architecture-, noise source-, and quantum state-independent. We implement this method on a superconducting qubit and evaluate the increase in reconstruction fidelity for QST. We characterize the performance of the method by varying important noise sources, such as suboptimal readout signal amplification, insufficient resonator photon population, off-resonant qubit drive, and effectively shortened T1 and T2 coherence. As a result, we identified noise sources for which readout error mitigation worked well, and observed decreases in readout infidelity by a factor of up to 30. Significant efforts have been dedicated to mitigate gate errors in quantum devices, while comparatively little attention has been given to the increasing issue of readout errors. The authors present an explicit protocol for comprehensive readout error mitigation with quantum state tomography, and demonstrate its applicability experimentally on a superconducting qubit device.
{"title":"Readout error mitigated quantum state tomography tested on superconducting qubits","authors":"Adrian Skasberg Aasen, Andras Di Giovanni, Hannes Rotzinger, Alexey V. Ustinov, Martin Gärttner","doi":"10.1038/s42005-024-01790-8","DOIUrl":"10.1038/s42005-024-01790-8","url":null,"abstract":"Quantum technologies rely heavily on accurate control and reliable readout of quantum systems. Current experiments are limited by numerous sources of noise that can only be partially captured by simple analytical models and additional characterization of the noise sources is required. We test the ability of readout error mitigation to correct noise found in systems composed of quantum two-level objects (qubits). To probe the limit of such methods, we designed a beyond-classical readout error mitigation protocol based on quantum state tomography (QST), which estimates the density matrix of a quantum system, and quantum detector tomography (QDT), which characterizes the measurement procedure. By treating readout error mitigation in the context of state tomography the method becomes largely readout mode-, architecture-, noise source-, and quantum state-independent. We implement this method on a superconducting qubit and evaluate the increase in reconstruction fidelity for QST. We characterize the performance of the method by varying important noise sources, such as suboptimal readout signal amplification, insufficient resonator photon population, off-resonant qubit drive, and effectively shortened T1 and T2 coherence. As a result, we identified noise sources for which readout error mitigation worked well, and observed decreases in readout infidelity by a factor of up to 30. Significant efforts have been dedicated to mitigate gate errors in quantum devices, while comparatively little attention has been given to the increasing issue of readout errors. The authors present an explicit protocol for comprehensive readout error mitigation with quantum state tomography, and demonstrate its applicability experimentally on a superconducting qubit device.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-11"},"PeriodicalIF":5.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01790-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182134","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 : 2024-09-06DOI: 10.1038/s42005-024-01714-6
Giulio Tani Raffaelli, Margherita Lalli, Francesca Tria
Urn models for innovation capture fundamental empirical laws shared by several real-world processes. The so-called urn model with triggering includes, as particular cases, the urn representation of the two-parameter Poisson-Dirichlet process and the Dirichlet process, seminal in Bayesian non-parametric inference. In this work, we leverage this connection to introduce a general approach for quantifying closeness between symbolic sequences and test it within the framework of the authorship attribution problem. The method demonstrates high accuracy when compared to other related methods in different scenarios, featuring a substantial gain in computational efficiency and theoretical transparency. Beyond the practical convenience, this work demonstrates how the recently established connection between urn models and non-parametric Bayesian inference can pave the way for designing more efficient inference methods. In particular, the hybrid approach that we propose allows us to relax the exchangeability hypothesis, which can be particularly relevant for systems exhibiting complex correlation patterns and non-stationary dynamics. A class of urn-based models accounts for stochastic regularities observed in systems that exhibit innovation in diverse forms and temporal scales, from the appearance of new organisms to the evolution of language to daily new experiences. The authors investigate the predictive power of those models in inference problems, addressing the authorship attribution task as a case study.
{"title":"Inference through innovation processes tested in the authorship attribution task","authors":"Giulio Tani Raffaelli, Margherita Lalli, Francesca Tria","doi":"10.1038/s42005-024-01714-6","DOIUrl":"10.1038/s42005-024-01714-6","url":null,"abstract":"Urn models for innovation capture fundamental empirical laws shared by several real-world processes. The so-called urn model with triggering includes, as particular cases, the urn representation of the two-parameter Poisson-Dirichlet process and the Dirichlet process, seminal in Bayesian non-parametric inference. In this work, we leverage this connection to introduce a general approach for quantifying closeness between symbolic sequences and test it within the framework of the authorship attribution problem. The method demonstrates high accuracy when compared to other related methods in different scenarios, featuring a substantial gain in computational efficiency and theoretical transparency. Beyond the practical convenience, this work demonstrates how the recently established connection between urn models and non-parametric Bayesian inference can pave the way for designing more efficient inference methods. In particular, the hybrid approach that we propose allows us to relax the exchangeability hypothesis, which can be particularly relevant for systems exhibiting complex correlation patterns and non-stationary dynamics. A class of urn-based models accounts for stochastic regularities observed in systems that exhibit innovation in diverse forms and temporal scales, from the appearance of new organisms to the evolution of language to daily new experiences. The authors investigate the predictive power of those models in inference problems, addressing the authorship attribution task as a case study.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01714-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182132","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 : 2024-09-06DOI: 10.1038/s42005-024-01792-6
K. V. S. Chaithanya, Aleksandra Ardaševa, Oliver J. Meacock, William M. Durham, Sumesh P. Thampi, Amin Doostmohammadi
Collectively moving cellular systems often contain a proportion of dead cells or non-motile genotypes. When mixed, nematically aligning motile and non-motile agents are known to segregate spontaneously. However, the role that topological defects and active stresses play in shaping the distribution of the two phases remains unresolved. In this study, we investigate the behaviour of a two-dimensional binary mixture of active and passive nematic fluids to understand how topological defects are transported between the two phases and, ultimately, how this leads to the segregation of topological charges. When the activity of the motile phase is large, and the tension at the interface of motile and non-motile phases is weak, we find that the active phase tends to accumulate +1/2 defects and expel −1/2 defects so that the motile phase develops a net positive charge. Conversely, when the activity of the motile phase is comparatively small and interfacial tension is strong, the opposite occurs so that the active phase develops a net negative charge. We then use these simulations to develop a physical intuition of the underlying processes that drive the charge segregation. Lastly, we quantify the sensitivity of this process on the other model parameters, by exploring the effect that anchoring strength, orientational elasticity, friction, and volume fraction of the motile phase have on topological charge segregation. As +1/2 and −1/2 defects have very different effects on interface morphology and fluid transport, this study offers new insights into the spontaneous pattern formation that occurs when motile and non-motile cells interact. Collectively moving cellular systems often contain both motile and non-motile genotypes, and when mixed, these agents segregate spontaneously. The study reveals that the segregation of topological charges between these agents depends on activity and interfacial tension, with high activity and low tension favoring a positively charged motile phase.
{"title":"Transport of topological defects in a biphasic mixture of active and passive nematic fluids","authors":"K. V. S. Chaithanya, Aleksandra Ardaševa, Oliver J. Meacock, William M. Durham, Sumesh P. Thampi, Amin Doostmohammadi","doi":"10.1038/s42005-024-01792-6","DOIUrl":"10.1038/s42005-024-01792-6","url":null,"abstract":"Collectively moving cellular systems often contain a proportion of dead cells or non-motile genotypes. When mixed, nematically aligning motile and non-motile agents are known to segregate spontaneously. However, the role that topological defects and active stresses play in shaping the distribution of the two phases remains unresolved. In this study, we investigate the behaviour of a two-dimensional binary mixture of active and passive nematic fluids to understand how topological defects are transported between the two phases and, ultimately, how this leads to the segregation of topological charges. When the activity of the motile phase is large, and the tension at the interface of motile and non-motile phases is weak, we find that the active phase tends to accumulate +1/2 defects and expel −1/2 defects so that the motile phase develops a net positive charge. Conversely, when the activity of the motile phase is comparatively small and interfacial tension is strong, the opposite occurs so that the active phase develops a net negative charge. We then use these simulations to develop a physical intuition of the underlying processes that drive the charge segregation. Lastly, we quantify the sensitivity of this process on the other model parameters, by exploring the effect that anchoring strength, orientational elasticity, friction, and volume fraction of the motile phase have on topological charge segregation. As +1/2 and −1/2 defects have very different effects on interface morphology and fluid transport, this study offers new insights into the spontaneous pattern formation that occurs when motile and non-motile cells interact. Collectively moving cellular systems often contain both motile and non-motile genotypes, and when mixed, these agents segregate spontaneously. The study reveals that the segregation of topological charges between these agents depends on activity and interfacial tension, with high activity and low tension favoring a positively charged motile phase.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-12"},"PeriodicalIF":5.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01792-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142182133","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 : 2024-09-05DOI: 10.1038/s42005-024-01777-5
Na Sun, Weixuan Zhang, Hao Yuan, Xiangdong Zhang
Bound states in the continuum (BICs), referring to spatially localized bound states with energies falling within the range of extended modes, have been extensively investigated in single-particle systems, leading to diverse applications in photonics, acoustics, and other classical-wave systems. Recently, there has been theoretical interest in exploring many-body BICs in interacting quantum systems, which necessitate the careful design of impurity potentials or spatial profiles of interaction. Here, we propose a type of many-body BICs localized at boundaries, which can be purely induced by the uniform onsite interaction without requiring any specific design of impurity potential or nonlocal interaction. We numerically show that three or more interacting bosons can concentrate on the boundary of a homogeneous one-dimensional lattice, which is absent at single- and two-particle counterparts. Moreover, the eigenenergy of multi-boson bound states can embed within the continuous energy spectra of extended scattering states, thereby giving rise to interaction-induced boundary many-body BICs. Furthermore, by mapping Fock states of three and four bosons to nonlinear circuit networks, we experimentally simulate boundary many-body BICs. Our findings enrich the comprehension of correlated BICs beyond the single-particle level, and have the potential to inspire future investigations on exploring many-body BICs. Bound states in the continuum (BICs) have been extensively investigated in single-particle systems, leading to diverse applications in photonics, acoustics, and other classical-wave systems. Here, the authors propose a type of interaction-induced many-body BICs at boundaries and experimentally simulate these boundary many-body BICs using nonlinear circuit networks.
{"title":"Boundary-localized many-body bound states in the continuum","authors":"Na Sun, Weixuan Zhang, Hao Yuan, Xiangdong Zhang","doi":"10.1038/s42005-024-01777-5","DOIUrl":"10.1038/s42005-024-01777-5","url":null,"abstract":"Bound states in the continuum (BICs), referring to spatially localized bound states with energies falling within the range of extended modes, have been extensively investigated in single-particle systems, leading to diverse applications in photonics, acoustics, and other classical-wave systems. Recently, there has been theoretical interest in exploring many-body BICs in interacting quantum systems, which necessitate the careful design of impurity potentials or spatial profiles of interaction. Here, we propose a type of many-body BICs localized at boundaries, which can be purely induced by the uniform onsite interaction without requiring any specific design of impurity potential or nonlocal interaction. We numerically show that three or more interacting bosons can concentrate on the boundary of a homogeneous one-dimensional lattice, which is absent at single- and two-particle counterparts. Moreover, the eigenenergy of multi-boson bound states can embed within the continuous energy spectra of extended scattering states, thereby giving rise to interaction-induced boundary many-body BICs. Furthermore, by mapping Fock states of three and four bosons to nonlinear circuit networks, we experimentally simulate boundary many-body BICs. Our findings enrich the comprehension of correlated BICs beyond the single-particle level, and have the potential to inspire future investigations on exploring many-body BICs. Bound states in the continuum (BICs) have been extensively investigated in single-particle systems, leading to diverse applications in photonics, acoustics, and other classical-wave systems. Here, the authors propose a type of interaction-induced many-body BICs at boundaries and experimentally simulate these boundary many-body BICs using nonlinear circuit networks.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01777-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142137880","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 : 2024-09-04DOI: 10.1038/s42005-024-01789-1
Riyi Zheng, Jing Lin, Jialuo Liang, Kun Ding, Jiuyang Lu, Weiyin Deng, Manzhu Ke, Xueqin Huang, Zhengyou Liu
The gap in spectra of a physical system is fundamental in physics, while gap topology further restricts possible occurrent gaps of topological boundary states. The emergence of non-Hermiticity unveils a unique gap type known as the point gap, which forecasts the wavefunction localization, known as the non-Hermitian skin effect. Therefore, experimentally identifying the point gap in the complex frequency plane through a real operating frequency can become a tool for the systematic investigation of skin effects. Here, we utilize a Weyl phononic crystal to demonstrate that the point gap constituted by bulk and Fermi-arc surface states can be observed experimentally by a real-space field mapping technique. The identified point gaps forecast various skin effects and their evolutions. We further experimentally demonstrate the hinge skin effect in a parallelogram structure. Our work provides a feasible recipe to explore point gap topology experimentally in a variety of systems and certainly stimulates the research on skin effects in three-dimensional systems. Point gap is signature of non-Hermitian systems, but the experimental identification of nontrivial point gaps is elusive. Here, the authors use a Weyl phononic crystal to demonstrate that the point gap constituted by bulk and Fermi-arc surface states can be observed experimentally by a real-space field mapping technique and discover various skin effects and their evolutions.
{"title":"Experimental probe of point gap topology from non-Hermitian Fermi-arcs","authors":"Riyi Zheng, Jing Lin, Jialuo Liang, Kun Ding, Jiuyang Lu, Weiyin Deng, Manzhu Ke, Xueqin Huang, Zhengyou Liu","doi":"10.1038/s42005-024-01789-1","DOIUrl":"10.1038/s42005-024-01789-1","url":null,"abstract":"The gap in spectra of a physical system is fundamental in physics, while gap topology further restricts possible occurrent gaps of topological boundary states. The emergence of non-Hermiticity unveils a unique gap type known as the point gap, which forecasts the wavefunction localization, known as the non-Hermitian skin effect. Therefore, experimentally identifying the point gap in the complex frequency plane through a real operating frequency can become a tool for the systematic investigation of skin effects. Here, we utilize a Weyl phononic crystal to demonstrate that the point gap constituted by bulk and Fermi-arc surface states can be observed experimentally by a real-space field mapping technique. The identified point gaps forecast various skin effects and their evolutions. We further experimentally demonstrate the hinge skin effect in a parallelogram structure. Our work provides a feasible recipe to explore point gap topology experimentally in a variety of systems and certainly stimulates the research on skin effects in three-dimensional systems. Point gap is signature of non-Hermitian systems, but the experimental identification of nontrivial point gaps is elusive. Here, the authors use a Weyl phononic crystal to demonstrate that the point gap constituted by bulk and Fermi-arc surface states can be observed experimentally by a real-space field mapping technique and discover various skin effects and their evolutions.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01789-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130458","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 : 2024-09-03DOI: 10.1038/s42005-024-01776-6
Paweł Ordyna, Carsten Bähtz, Erik Brambrink, Michael Bussmann, Alejandro Laso Garcia, Marco Garten, Lennart Gaus, Sebastian Göde, Jörg Grenzer, Christian Gutt, Hauke Höppner, Lingen Huang, Uwe Hübner, Oliver Humphries, Brian Edward Marré, Josefine Metzkes-Ng, Thomas Miethlinger, Motoaki Nakatsutsumi, Özgül Öztürk, Xiayun Pan, Franziska Paschke-Brühl, Alexander Pelka, Irene Prencipe, Thomas R. Preston, Lisa Randolph, Hans-Peter Schlenvoigt, Jan-Patrick Schwinkendorf, Michal Šmíd, Sebastian Starke, Radka Štefaníková, Erik Thiessenhusen, Toma Toncian, Karl Zeil, Ulrich Schramm, Thomas E. Cowan, Thomas Kluge
Ultra-intense lasers that ionize atoms and accelerate electrons in solids to near the speed of light can lead to kinetic instabilities that alter the laser absorption and subsequent electron transport, isochoric heating, and ion acceleration. These instabilities can be difficult to characterize, but X-ray scattering at keV photon energies allows for their visualization with femtosecond temporal resolution on the few nanometer mesoscale. Here, we perform such experiment on laser-driven flat silicon membranes that shows the development of structure with a dominant scale of 60 nm in the plane of the laser axis and laser polarization, and 95 nm in the vertical direction with a growth rate faster than 0.1 fs−1. Combining the XFEL experiments with simulations provides a complete picture of the structural evolution of ultra-fast laser-induced plasma density development, indicating the excitation of plasmons and a filamentation instability. Particle-in-cell simulations confirm that these signals are due to an oblique two-stream filamentation instability. These findings provide new insight into ultra-fast instability and heating processes in solids under extreme conditions at the nanometer level with possible implications for laser particle acceleration, inertial confinement fusion, and laboratory astrophysics. Ultrafast relativistic plasma instabilities accompany and influence laser matter interactions that accelerate particlebeams with potential applications in e.g radiotherapy or fussion fast ignition scenarios. Here, the authors use Small Angle X-ray Scattering to observe such instabilities on a femtosecond, tens of nanometer scale in solids, and draw conclusions on the underlying plasma dynamics.
超强激光可将固体中的原子电离和电子加速到接近光速，从而导致动力学不稳定性，改变激光吸收和随后的电子传输、等速加热和离子加速。这些不稳定性可能难以表征，但在 keV 光子能量下的 X 射线散射可以在几纳米的中尺度上以飞秒级的时间分辨率将其可视化。在这里，我们在激光驱动的平面硅膜上进行了这样的实验，结果表明，在激光轴和激光偏振平面上，结构的主要尺度为 60 纳米，在垂直方向上为 95 纳米，其增长速度快于 0.1 fs-1。将 XFEL 实验与模拟相结合，可以全面了解超快激光诱导等离子体密度发展的结构演变，表明等离子体的激发和丝状不稳定性。粒子间模拟证实，这些信号是由斜双流丝状不稳定性引起的。这些发现为纳米级极端条件下固体中的超快不稳定性和加热过程提供了新的视角，可能对激光粒子加速、惯性约束聚变和实验室天体物理学产生影响。超快相对论等离子体不稳定性伴随并影响着激光物质相互作用，从而加速粒子束，并有可能应用于放射治疗或冲击快速点火等场景。在这里，作者利用小角 X 射线散射观测了固体中飞秒级、数十纳米级的不稳定性，并得出了有关潜在等离子体动力学的结论。
{"title":"Visualizing plasmons and ultrafast kinetic instabilities in laser-driven solids using X-ray scattering","authors":"Paweł Ordyna, Carsten Bähtz, Erik Brambrink, Michael Bussmann, Alejandro Laso Garcia, Marco Garten, Lennart Gaus, Sebastian Göde, Jörg Grenzer, Christian Gutt, Hauke Höppner, Lingen Huang, Uwe Hübner, Oliver Humphries, Brian Edward Marré, Josefine Metzkes-Ng, Thomas Miethlinger, Motoaki Nakatsutsumi, Özgül Öztürk, Xiayun Pan, Franziska Paschke-Brühl, Alexander Pelka, Irene Prencipe, Thomas R. Preston, Lisa Randolph, Hans-Peter Schlenvoigt, Jan-Patrick Schwinkendorf, Michal Šmíd, Sebastian Starke, Radka Štefaníková, Erik Thiessenhusen, Toma Toncian, Karl Zeil, Ulrich Schramm, Thomas E. Cowan, Thomas Kluge","doi":"10.1038/s42005-024-01776-6","DOIUrl":"10.1038/s42005-024-01776-6","url":null,"abstract":"Ultra-intense lasers that ionize atoms and accelerate electrons in solids to near the speed of light can lead to kinetic instabilities that alter the laser absorption and subsequent electron transport, isochoric heating, and ion acceleration. These instabilities can be difficult to characterize, but X-ray scattering at keV photon energies allows for their visualization with femtosecond temporal resolution on the few nanometer mesoscale. Here, we perform such experiment on laser-driven flat silicon membranes that shows the development of structure with a dominant scale of 60 nm in the plane of the laser axis and laser polarization, and 95 nm in the vertical direction with a growth rate faster than 0.1 fs−1. Combining the XFEL experiments with simulations provides a complete picture of the structural evolution of ultra-fast laser-induced plasma density development, indicating the excitation of plasmons and a filamentation instability. Particle-in-cell simulations confirm that these signals are due to an oblique two-stream filamentation instability. These findings provide new insight into ultra-fast instability and heating processes in solids under extreme conditions at the nanometer level with possible implications for laser particle acceleration, inertial confinement fusion, and laboratory astrophysics. Ultrafast relativistic plasma instabilities accompany and influence laser matter interactions that accelerate particlebeams with potential applications in e.g radiotherapy or fussion fast ignition scenarios. Here, the authors use Small Angle X-ray Scattering to observe such instabilities on a femtosecond, tens of nanometer scale in solids, and draw conclusions on the underlying plasma dynamics.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01776-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130460","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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