Pub Date : 2024-10-14DOI: 10.1038/s42005-024-01831-2
Tytti Kärki, Into Pääkkönen, Nikos Kyriakopoulos, Jaakko V. I. Timonen
Sessile drops are ubiquitous and important in technological applications. While dynamics of liquid drops have been studied under confinement, the possibility of creating sessile drops with reduced dimensionality has not been explored. Here, we demonstrate a quasi-two-dimensional (Q2D) analogy for axisymmetric sessile three-dimensional (3D) drops. The Q2D drops are created by confining liquids between parallel vertical walls, forming low aspect ratio capillary bridges deformed by gravity. Stationary Q2D drops adopt projected shapes analogous to 3D sessile drops, ranging from circular drops to puddles. When moving, the Q2D drops exhibit capillary and fluid mechanical behaviours conceptually analogous to 3D drops, including impacts and sliding. The Q2D drops also exhibit more complex phenomena such as levitation, various instabilities and pattern formation when subjected to external electric, magnetic and flow fields. The 3D-Q2D analogy suggests that the diverse and often complicated phenomena observed in 3D drops can be studied in the simplified Q2D geometry. Additionally, the Q2D confinement analogy allows exploring phenomena arising from the reduced dimensionality and the altered boundary conditions. Axisymmetric sessile liquid drops are everywhere around us and important in numerous technological applications. Here the authors experimentally prepare quasi-two-dimensional sessile drops and show that they display many similar features as the traditional axisymmetric sessile drops, including analogous equilibrium shape, dynamics, and instabilities.
{"title":"Quasi-two-dimensional pseudo-sessile drops","authors":"Tytti Kärki, Into Pääkkönen, Nikos Kyriakopoulos, Jaakko V. I. Timonen","doi":"10.1038/s42005-024-01831-2","DOIUrl":"10.1038/s42005-024-01831-2","url":null,"abstract":"Sessile drops are ubiquitous and important in technological applications. While dynamics of liquid drops have been studied under confinement, the possibility of creating sessile drops with reduced dimensionality has not been explored. Here, we demonstrate a quasi-two-dimensional (Q2D) analogy for axisymmetric sessile three-dimensional (3D) drops. The Q2D drops are created by confining liquids between parallel vertical walls, forming low aspect ratio capillary bridges deformed by gravity. Stationary Q2D drops adopt projected shapes analogous to 3D sessile drops, ranging from circular drops to puddles. When moving, the Q2D drops exhibit capillary and fluid mechanical behaviours conceptually analogous to 3D drops, including impacts and sliding. The Q2D drops also exhibit more complex phenomena such as levitation, various instabilities and pattern formation when subjected to external electric, magnetic and flow fields. The 3D-Q2D analogy suggests that the diverse and often complicated phenomena observed in 3D drops can be studied in the simplified Q2D geometry. Additionally, the Q2D confinement analogy allows exploring phenomena arising from the reduced dimensionality and the altered boundary conditions. Axisymmetric sessile liquid drops are everywhere around us and important in numerous technological applications. Here the authors experimentally prepare quasi-two-dimensional sessile drops and show that they display many similar features as the traditional axisymmetric sessile drops, including analogous equilibrium shape, dynamics, and instabilities.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-9"},"PeriodicalIF":5.4,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01831-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-14DOI: 10.1038/s42005-024-01811-6
Vasilis Belis, Kinga Anna Woźniak, Ema Puljak, Panagiotis Barkoutsos, Günther Dissertori, Michele Grossi, Maurizio Pierini, Florentin Reiter, Ivano Tavernelli, Sofia Vallecorsa
The ongoing quest to discover new phenomena at the LHC necessitates the continuous development of algorithms and technologies. Established approaches like machine learning, along with emerging technologies such as quantum computing show promise in the enhancement of experimental capabilities. In this work, we propose a strategy for anomaly detection tasks at the LHC based on unsupervised quantum machine learning, and demonstrate its effectiveness in identifying new phenomena. The designed quantum models-an unsupervised kernel machine and two clustering algorithms-are trained to detect new-physics events using a latent representation of LHC data, generated by an autoencoder designed to accommodate current quantum hardware limitations on problem size. For kernel-based anomaly detection, we implement an instance of the model on a quantum computer, and we identify a regime where it significantly outperforms its classical counterparts. We show that the observed performance enhancement is related to the quantum resources utilised by the model. The ongoing quest in particle physics to discover fundamentally new phenomena necessitates the continuous development of algorithms and technologies. The authors propose a methodology based on quantum machine learning that can identify new phenomena in proton collision experiments, showing that it can outperform its classical counterparts when sufficient quantum computing resources are utilized.
{"title":"Quantum anomaly detection in the latent space of proton collision events at the LHC","authors":"Vasilis Belis, Kinga Anna Woźniak, Ema Puljak, Panagiotis Barkoutsos, Günther Dissertori, Michele Grossi, Maurizio Pierini, Florentin Reiter, Ivano Tavernelli, Sofia Vallecorsa","doi":"10.1038/s42005-024-01811-6","DOIUrl":"10.1038/s42005-024-01811-6","url":null,"abstract":"The ongoing quest to discover new phenomena at the LHC necessitates the continuous development of algorithms and technologies. Established approaches like machine learning, along with emerging technologies such as quantum computing show promise in the enhancement of experimental capabilities. In this work, we propose a strategy for anomaly detection tasks at the LHC based on unsupervised quantum machine learning, and demonstrate its effectiveness in identifying new phenomena. The designed quantum models-an unsupervised kernel machine and two clustering algorithms-are trained to detect new-physics events using a latent representation of LHC data, generated by an autoencoder designed to accommodate current quantum hardware limitations on problem size. For kernel-based anomaly detection, we implement an instance of the model on a quantum computer, and we identify a regime where it significantly outperforms its classical counterparts. We show that the observed performance enhancement is related to the quantum resources utilised by the model. The ongoing quest in particle physics to discover fundamentally new phenomena necessitates the continuous development of algorithms and technologies. The authors propose a methodology based on quantum machine learning that can identify new phenomena in proton collision experiments, showing that it can outperform its classical counterparts when sufficient quantum computing resources are utilized.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-11"},"PeriodicalIF":5.4,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01811-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-14DOI: 10.1038/s42005-024-01830-3
Helcio Felippe, Federico Battiston, Alec Kirkley
A wide range of tasks in network analysis, such as clustering network populations or identifying anomalies in temporal graph streams, require a measure of the similarity between two graphs. To provide a meaningful data summary for downstream scientific analyses, the graph similarity measures used for these tasks must be principled, interpretable, and capable of distinguishing meaningful overlapping network structure from statistical noise at different scales of interest. Here we derive a family of graph mutual information measures that satisfy these criteria and are constructed using only fundamental information theoretic principles. Our measures capture the information shared among networks according to different encodings of their structural information, with our mesoscale mutual information measure allowing for network comparison under any specified network coarse-graining. We test our measures in a range of applications on real and synthetic network data, finding that they effectively highlight intuitive aspects of network similarity across scales in a variety of systems. Graph similarity measures are essential for downstream tasks including clustering, embedding, and regression with populations of networks. Here the authors derive a family of graph mutual information measures that allow for a principled, interpretable, and efficient comparison of networks at multiple scales.
{"title":"Network mutual information measures for graph similarity","authors":"Helcio Felippe, Federico Battiston, Alec Kirkley","doi":"10.1038/s42005-024-01830-3","DOIUrl":"10.1038/s42005-024-01830-3","url":null,"abstract":"A wide range of tasks in network analysis, such as clustering network populations or identifying anomalies in temporal graph streams, require a measure of the similarity between two graphs. To provide a meaningful data summary for downstream scientific analyses, the graph similarity measures used for these tasks must be principled, interpretable, and capable of distinguishing meaningful overlapping network structure from statistical noise at different scales of interest. Here we derive a family of graph mutual information measures that satisfy these criteria and are constructed using only fundamental information theoretic principles. Our measures capture the information shared among networks according to different encodings of their structural information, with our mesoscale mutual information measure allowing for network comparison under any specified network coarse-graining. We test our measures in a range of applications on real and synthetic network data, finding that they effectively highlight intuitive aspects of network similarity across scales in a variety of systems. Graph similarity measures are essential for downstream tasks including clustering, embedding, and regression with populations of networks. Here the authors derive a family of graph mutual information measures that allow for a principled, interpretable, and efficient comparison of networks at multiple scales.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-12"},"PeriodicalIF":5.4,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01830-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-14DOI: 10.1038/s42005-024-01834-z
Peter Deák, Song Li, Adam Gali
Defect-related spin-to-photon interfaces in silicon promise the realization of quantum repeaters by combining advanced semiconductor and photonics technologies. Recently, controlled creation/erasure of simple carbon interstitial defects have been successfully realised in silicon. This defect has a stable structure near room temperature and coherently emits in the wave-length where the signal loss is minimal in optical fibres used in communication technologies. Our in-depth theoretical characterization confirms the assignment of the observed emission to the neutral charge state of this defect, as arising due to the recombination of a bound exciton. We also identified a metastable triplet state that could be applied as a quantum memory. Based on the analysis of the electronic structure of the defect and its similarities to a known optically detected magnetic resonance centre in silicon, we propose that a carbon interstitial can act as a quantum bit and may realize a spin-to-photon interface in complementary metal-oxide semiconductor-compatible platforms. This work presents a theoretical investigation of the single carbon interstitial (Ci) defect in silicon as a potential candidate for spin-photon interfaces. Computed charge transition levels and optical properties show good agreement with the experimental results and allow assigning the experimentally observed telecom zero-phonon emission (1448 nm) to the neutral Ci defect.
硅中与缺陷相关的自旋光子界面有望通过结合先进的半导体和光子技术实现量子中继器。最近，在硅中成功实现了简单碳间隙缺陷的受控创建/测量。这种缺陷在室温附近具有稳定的结构，并在通信技术中使用的光纤信号损失最小的波长上相干发射。我们深入的理论分析证实，所观察到的发射归因于该缺陷的中性电荷态，是由束缚激子的重组引起的。我们还发现了一种可用作量子存储器的瞬变三重态。基于对该缺陷电子结构的分析及其与硅中已知的光学检测磁共振中心的相似性，我们提出碳间隙可以充当量子位，并可能在互补金属氧化物半导体兼容平台中实现自旋到光子的接口。本研究对硅中的单个碳间隙（Ci）缺陷作为自旋光子接口的潜在候选者进行了理论研究。计算的电荷转移水平和光学特性与实验结果显示出良好的一致性，并允许将实验观测到的电信零光子发射（1448 nm）归因于中性 Ci 缺陷。
{"title":"Quantum bit with telecom wave-length emission from a simple defect in Si","authors":"Peter Deák, Song Li, Adam Gali","doi":"10.1038/s42005-024-01834-z","DOIUrl":"10.1038/s42005-024-01834-z","url":null,"abstract":"Defect-related spin-to-photon interfaces in silicon promise the realization of quantum repeaters by combining advanced semiconductor and photonics technologies. Recently, controlled creation/erasure of simple carbon interstitial defects have been successfully realised in silicon. This defect has a stable structure near room temperature and coherently emits in the wave-length where the signal loss is minimal in optical fibres used in communication technologies. Our in-depth theoretical characterization confirms the assignment of the observed emission to the neutral charge state of this defect, as arising due to the recombination of a bound exciton. We also identified a metastable triplet state that could be applied as a quantum memory. Based on the analysis of the electronic structure of the defect and its similarities to a known optically detected magnetic resonance centre in silicon, we propose that a carbon interstitial can act as a quantum bit and may realize a spin-to-photon interface in complementary metal-oxide semiconductor-compatible platforms. This work presents a theoretical investigation of the single carbon interstitial (Ci) defect in silicon as a potential candidate for spin-photon interfaces. Computed charge transition levels and optical properties show good agreement with the experimental results and allow assigning the experimentally observed telecom zero-phonon emission (1448 nm) to the neutral Ci defect.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-6"},"PeriodicalIF":5.4,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01834-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-13DOI: 10.1038/s42005-024-01817-0
Joscha Mecke, Yongxiang Gao, Gerhard Gompper, Marisol Ripoll
Chiral active fluids show the emergence of a turbulent behaviour characterised by multiple dynamic vortices whose maximum size varies for each experimental system, depending on conditions not yet identified. We propose and develop an approach to model the effect of friction close to a surface in a particle based hydrodynamic simulation method in two dimensions, in which the friction coefficient can be related to the system parameters and to the emergence of a damping length. This length is system dependent, limits the size of the emergent vortices, and influences other relevant system properties such as the actuated velocity, rotational diffusion, or the cutoff of the energy spectra. Comparison of simulation and experimental results of a large ensemble of rotating colloids sedimented on a surface shows a good agreement, which demonstrates the predictive capabilities of the approach, which can be applied to a wider class of quasi-two-dimensional systems with friction. The dynamics of chiral active fluids is characterised by a multitude of interacting dynamic vortices whose maximum size varies for each system. Here we show how the friction induced by the substrate is related to a damping length which is ultimately responsible of limiting the maximum size of the vortices.
{"title":"Chiral active systems near a substrate: Emergent damping length controlled by fluid friction","authors":"Joscha Mecke, Yongxiang Gao, Gerhard Gompper, Marisol Ripoll","doi":"10.1038/s42005-024-01817-0","DOIUrl":"10.1038/s42005-024-01817-0","url":null,"abstract":"Chiral active fluids show the emergence of a turbulent behaviour characterised by multiple dynamic vortices whose maximum size varies for each experimental system, depending on conditions not yet identified. We propose and develop an approach to model the effect of friction close to a surface in a particle based hydrodynamic simulation method in two dimensions, in which the friction coefficient can be related to the system parameters and to the emergence of a damping length. This length is system dependent, limits the size of the emergent vortices, and influences other relevant system properties such as the actuated velocity, rotational diffusion, or the cutoff of the energy spectra. Comparison of simulation and experimental results of a large ensemble of rotating colloids sedimented on a surface shows a good agreement, which demonstrates the predictive capabilities of the approach, which can be applied to a wider class of quasi-two-dimensional systems with friction. The dynamics of chiral active fluids is characterised by a multitude of interacting dynamic vortices whose maximum size varies for each system. Here we show how the friction induced by the substrate is related to a damping length which is ultimately responsible of limiting the maximum size of the vortices.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01817-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1038/s42005-024-01819-y
Lena Mangold, Camille Roth
Network analysis is often enriched by including an examination of node metadata. In the context of understanding the mesoscale of networks it is often assumed that node groups based on metadata and node groups based on connectivity patterns are intrinsically linked. This assumption is increasingly being challenged, whereby metadata might be entirely unrelated to structure or, similarly, multiple sets of metadata might be relevant to the structure of a network in different ways. We propose the metablox tool to quantify the relationship between a network’s node metadata and its mesoscale structure, measuring the strength of the relationship and the type of structural arrangement exhibited by the metadata. We show on a number of synthetic and empirical networks that our tool distinguishes relevant metadata and allows for this in a comparative setting, demonstrating that it can be used as part of systematic meta analyses for the comparison of networks from different domains. Network data often includes categorical node attributes whose relevance to the network’s structure is often unknown. Here the authors propose the metablox (metadata block structure exploration) tool, to quantify the relationship between categorical node metadata and the block structure of the network, using Stochastic block models and description length.
{"title":"Quantifying metadata relevance to network block structure using description length","authors":"Lena Mangold, Camille Roth","doi":"10.1038/s42005-024-01819-y","DOIUrl":"10.1038/s42005-024-01819-y","url":null,"abstract":"Network analysis is often enriched by including an examination of node metadata. In the context of understanding the mesoscale of networks it is often assumed that node groups based on metadata and node groups based on connectivity patterns are intrinsically linked. This assumption is increasingly being challenged, whereby metadata might be entirely unrelated to structure or, similarly, multiple sets of metadata might be relevant to the structure of a network in different ways. We propose the metablox tool to quantify the relationship between a network’s node metadata and its mesoscale structure, measuring the strength of the relationship and the type of structural arrangement exhibited by the metadata. We show on a number of synthetic and empirical networks that our tool distinguishes relevant metadata and allows for this in a comparative setting, demonstrating that it can be used as part of systematic meta analyses for the comparison of networks from different domains. Network data often includes categorical node attributes whose relevance to the network’s structure is often unknown. Here the authors propose the metablox (metadata block structure exploration) tool, to quantify the relationship between categorical node metadata and the block structure of the network, using Stochastic block models and description length.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-14"},"PeriodicalIF":5.4,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01819-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443632","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}
Frustration hinders ideal local interactions in systems ranging from artificial spin ices with ice rules to mechanical metamaterials featuring regular floppy modes. While geometric frustrations have been known to promote complex ordered patterns in tessellated lattice structures, there is growing interest in global frustrations due to the topologically nontrivial geometry of metamaterials. However, multiferroic orders in globally frustrated metamaterials have remained elusive. Here, we present polar domain walls constrained in flexible mechanical metamaterials with global frustration and sequential symmetry breaking. We showcase that under simple compressive loading, competing interactions in globally frustrated metamaterials give rise to mixed deformations with high-order buckling modes described by an emergent order parameter. Utilizing an elastic mechanism model, we unveil the process of sequential symmetry breaking and capture the formation of polar domain walls exhibiting a chiral distribution within a multi-well potential landscape. We further demonstrate how to eliminate frustration through torsional loading, leading to symmetry restoration. These results provide insights into the intricate interactions between order and frustration, inspiring the modulation of domain walls in macroscopic systems. Elastic structures featuring tessellated rhombuses exhibit instability and heterogeneous patterns under compression. This study reveals how chiral orders emerge and can be suppressed by adjusting mismatches between local deformations and the overall geometry.
{"title":"Polar domain walls induced by sequential symmetry breaking in frustrated mechanical metamaterials","authors":"Yuan Zhou, Yafei Zhang, Zhixuan Wen, Chang Qing Chen","doi":"10.1038/s42005-024-01823-2","DOIUrl":"10.1038/s42005-024-01823-2","url":null,"abstract":"Frustration hinders ideal local interactions in systems ranging from artificial spin ices with ice rules to mechanical metamaterials featuring regular floppy modes. While geometric frustrations have been known to promote complex ordered patterns in tessellated lattice structures, there is growing interest in global frustrations due to the topologically nontrivial geometry of metamaterials. However, multiferroic orders in globally frustrated metamaterials have remained elusive. Here, we present polar domain walls constrained in flexible mechanical metamaterials with global frustration and sequential symmetry breaking. We showcase that under simple compressive loading, competing interactions in globally frustrated metamaterials give rise to mixed deformations with high-order buckling modes described by an emergent order parameter. Utilizing an elastic mechanism model, we unveil the process of sequential symmetry breaking and capture the formation of polar domain walls exhibiting a chiral distribution within a multi-well potential landscape. We further demonstrate how to eliminate frustration through torsional loading, leading to symmetry restoration. These results provide insights into the intricate interactions between order and frustration, inspiring the modulation of domain walls in macroscopic systems. Elastic structures featuring tessellated rhombuses exhibit instability and heterogeneous patterns under compression. This study reveals how chiral orders emerge and can be suppressed by adjusting mismatches between local deformations and the overall geometry.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01823-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1038/s42005-024-01826-z
Gang Chen
We recently demonstrated via experiments in hydrogels and at a single air-water interface the photomolecular effect: photons directly cleaving off water molecular clusters in the visible spectrum where bulk water has negligible absorption. To model single interface experiments, here we re-derive generalized boundary conditions for Maxwell equations by assuming a transition region of the electromagnetic fields across the interface, leading naturally to the Feibelman parameters used before to describe surface photoelectric and surface plasmon effects on metals. This generalization leads to modifications of the Fresnel coefficients and an expression for the surface absorptance that can reasonably explain trends in our single-interface experimental data on the angle and polarization dependence of the beam deflection. Our work provides further support for the existence of the photomolecular effect, suggests that surface absorption should exist in many materials, and lays a foundation for assessing the impacts of such surface absorption based on the Maxwell equations. The newly discovered photomolecular effect reveals that photons can evaporate water clusters in the visible spectrum where bulk water absorbs little. This work generalizes boundary conditions for Maxwell’s equations with Feibelman parameters and presents modified Fresnel coefficients and interfacial absorptance predicting trends consistent with experiments.
{"title":"Modeling photomolecular effect using generalized boundary conditions for Maxwell equations","authors":"Gang Chen","doi":"10.1038/s42005-024-01826-z","DOIUrl":"10.1038/s42005-024-01826-z","url":null,"abstract":"We recently demonstrated via experiments in hydrogels and at a single air-water interface the photomolecular effect: photons directly cleaving off water molecular clusters in the visible spectrum where bulk water has negligible absorption. To model single interface experiments, here we re-derive generalized boundary conditions for Maxwell equations by assuming a transition region of the electromagnetic fields across the interface, leading naturally to the Feibelman parameters used before to describe surface photoelectric and surface plasmon effects on metals. This generalization leads to modifications of the Fresnel coefficients and an expression for the surface absorptance that can reasonably explain trends in our single-interface experimental data on the angle and polarization dependence of the beam deflection. Our work provides further support for the existence of the photomolecular effect, suggests that surface absorption should exist in many materials, and lays a foundation for assessing the impacts of such surface absorption based on the Maxwell equations. The newly discovered photomolecular effect reveals that photons can evaporate water clusters in the visible spectrum where bulk water absorbs little. This work generalizes boundary conditions for Maxwell’s equations with Feibelman parameters and presents modified Fresnel coefficients and interfacial absorptance predicting trends consistent with experiments.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-10"},"PeriodicalIF":5.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01826-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443640","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}
A human cochlea is capable of continuously separating and amplifying sound of different frequencies to specific positions from 20 to 20,000 Hz, which makes it a high-resolution living sensor. The realization of cochlea-like structure for elastic waves in solids offers a highly desirable functionality on high throughput mechanical energy harvesting and sensing, but remains a challenging topic owing to narrow band and intricate configuration. Here we propose and demonstrate a generic framework of elastic cochlea on a thin plate, enabled by a pair of compact metafence layers. It is experimentally realized to harvest and separate flexural waves in quite a wide frequency range from 5.8 to 21.8 kHz, together with a continuous energy amplification exceeding one magnitude order. An enhanced mode, characterized by a near zero group velocity at a tailored cutoff width, is uncovered to illustrate the filtering and amplification physics. Moreover, complex information demultiplexing and undistorted decoding are further realized by harnessing the high-Q signal sensing and purification. The proposed prototype may stimulate substantial applications on information processing, non-destructive evaluation and other wave regulation scenarios. Cochlea is a high-resolution auditory transduction organ to distinguish sounds in both high sensitivity and broadband working frequency. The authors mimic a cochlea on a plate, which can separate, purify and decode complicated elastic waves in quite a compact way.
{"title":"Separating, purifying and decoding elastic waves by mimicking a cochlea on a thin plate","authors":"Yun Shi, Gaoxi Cai, Zhendong Sha, Meiying Zhao, Bing Li, Yongquan Liu","doi":"10.1038/s42005-024-01818-z","DOIUrl":"10.1038/s42005-024-01818-z","url":null,"abstract":"A human cochlea is capable of continuously separating and amplifying sound of different frequencies to specific positions from 20 to 20,000 Hz, which makes it a high-resolution living sensor. The realization of cochlea-like structure for elastic waves in solids offers a highly desirable functionality on high throughput mechanical energy harvesting and sensing, but remains a challenging topic owing to narrow band and intricate configuration. Here we propose and demonstrate a generic framework of elastic cochlea on a thin plate, enabled by a pair of compact metafence layers. It is experimentally realized to harvest and separate flexural waves in quite a wide frequency range from 5.8 to 21.8 kHz, together with a continuous energy amplification exceeding one magnitude order. An enhanced mode, characterized by a near zero group velocity at a tailored cutoff width, is uncovered to illustrate the filtering and amplification physics. Moreover, complex information demultiplexing and undistorted decoding are further realized by harnessing the high-Q signal sensing and purification. The proposed prototype may stimulate substantial applications on information processing, non-destructive evaluation and other wave regulation scenarios. Cochlea is a high-resolution auditory transduction organ to distinguish sounds in both high sensitivity and broadband working frequency. The authors mimic a cochlea on a plate, which can separate, purify and decode complicated elastic waves in quite a compact way.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":" ","pages":"1-8"},"PeriodicalIF":5.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01818-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142443615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-10DOI: 10.1038/s42005-024-01824-1
Marvin A. J. van Tilburg, Riccardo Farina, Victor T. van Lange, Wouter H. J. Peeters, Steffen Meder, Marvin M. Jansen, Marcel A. Verheijen, M. Vettori, Jonathan J. Finley, Erik. P. A. M. Bakkers, Jos. E. M. Haverkort
Hexagonal crystal phase silicon-germanium (hex-SiGe) features efficient direct bandgap emission between 1.5 and 3.4 µm. For expanding its application potential, the key challenge is to demonstrate material gain for enabling a hex-SiGe semiconductor laser. Here we report the transition from the spontaneous emission regime to the stimulated emission-dominated amplified spontaneous emission regime in the optically excited part of a hexagonal Si0.2Ge0.8 nanowire. We observe narrow resonance peaks arising above a spontaneous emission background, which show lasing signatures such as a threshold and a superlinear increase of the emission. A Hakki-Paoli analysis of the height of the cavity resonances provides the gain spectrum of hex-SiGe, showing evidence for a positive material gain. Measurements of the cavity line widths provide an independent assessment of the total cavity loss. While lasing has not been reached, the observation of optical amplification and amplified spontaneous emission provides a clear roadmap toward lasing in hexagonal SiGe. This opens a new pathway for the monolithic integration of a Si-compatible laser within electronic chips. Hexagonal silicon-germanium features efficient direct bandgap light emission. Here, the authors demonstrate the presence of stimulated emission and optical gain in hexagonal silicon germanium and provide a roadmap to reach lasing.
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