Computational fluid dynamics is both a thriving research field and a key tool for advanced industry applications. However, the simulation of turbulent flows in complex geometries is a compute-power intensive task due to the vast vector dimensions required by discretized meshes. We present a complete and self-consistent full-stack method to solve incompressible fluids with memory and run time scaling logarithmically in the mesh size. Our framework is based on matrix-product states, a compressed representation of quantum states. It is complete in that it solves for flows around immersed objects of arbitrary geometries, with non-trivial boundary conditions, and self-consistent in that it can retrieve the solution directly from the compressed encoding, i.e. without passing through the expensive dense-vector representation. This framework lays the foundation for a generation of more efficient solvers of real-life fluid problems. Simulating turbulent fluids is a major computational challenge, the main obstacle being the large size of discretized meshes required to accurately describe turbulent flows. The authors develop a quantum-inspired framework, based on matrix product states, to solve for flows around immersed bodies with complexity scaling logarithmically in the mesh size.
{"title":"Quantum-inspired framework for computational fluid dynamics","authors":"Raghavendra Dheeraj Peddinti, Stefano Pisoni, Alessandro Marini, Philippe Lott, Henrique Argentieri, Egor Tiunov, Leandro Aolita","doi":"10.1038/s42005-024-01623-8","DOIUrl":"10.1038/s42005-024-01623-8","url":null,"abstract":"Computational fluid dynamics is both a thriving research field and a key tool for advanced industry applications. However, the simulation of turbulent flows in complex geometries is a compute-power intensive task due to the vast vector dimensions required by discretized meshes. We present a complete and self-consistent full-stack method to solve incompressible fluids with memory and run time scaling logarithmically in the mesh size. Our framework is based on matrix-product states, a compressed representation of quantum states. It is complete in that it solves for flows around immersed objects of arbitrary geometries, with non-trivial boundary conditions, and self-consistent in that it can retrieve the solution directly from the compressed encoding, i.e. without passing through the expensive dense-vector representation. This framework lays the foundation for a generation of more efficient solvers of real-life fluid problems. Simulating turbulent fluids is a major computational challenge, the main obstacle being the large size of discretized meshes required to accurately describe turbulent flows. The authors develop a quantum-inspired framework, based on matrix product states, to solve for flows around immersed bodies with complexity scaling logarithmically in the mesh size.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01623-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140807338","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 : 2024-04-26DOI: 10.1038/s42005-024-01617-6
Zheng-Hong Li, Fei Yu, Zhen-Ya Li, M. Al-Amri, M. Suhail Zubairy
Cat states, as an important resource in the study of macroscopic quantum superposition and quantum information applications, have garnered widespread attention. To date, preparing large-sized optical cat states has remained challenging. We demonstrate that, by utilizing interaction-free measurement and the quantum Zeno effect, even a fragile quantum microscopic system can deterministically control and become entangled with strong light fields, thereby generating large-amplitude optical cat states. During the entire preparation process, our method ensures that the microscopic system functions within a weak field environment, so that its quantum property can be protected. Furthermore, we show that the preparation of cat states is possible even when the quantum microsystem suffers from significant photon loss, provided that optical losses from classical devices are kept low, which implies that the fidelity of the cat state can be enhanced by improvements to and the perfection of the classical optical system. In quantum physics, superposition—illustrated by Schrödinger’s cat being both dead and alive—inspires ‘cat states’, utilized in quantum technologies. The authors propose a theory where the optical state, through multiple indirect atom interactions in an interferometric setup, can generate large-amplitude optical cat states, advancing quantum applications.
{"title":"Method to deterministically generate large-amplitude optical cat states","authors":"Zheng-Hong Li, Fei Yu, Zhen-Ya Li, M. Al-Amri, M. Suhail Zubairy","doi":"10.1038/s42005-024-01617-6","DOIUrl":"10.1038/s42005-024-01617-6","url":null,"abstract":"Cat states, as an important resource in the study of macroscopic quantum superposition and quantum information applications, have garnered widespread attention. To date, preparing large-sized optical cat states has remained challenging. We demonstrate that, by utilizing interaction-free measurement and the quantum Zeno effect, even a fragile quantum microscopic system can deterministically control and become entangled with strong light fields, thereby generating large-amplitude optical cat states. During the entire preparation process, our method ensures that the microscopic system functions within a weak field environment, so that its quantum property can be protected. Furthermore, we show that the preparation of cat states is possible even when the quantum microsystem suffers from significant photon loss, provided that optical losses from classical devices are kept low, which implies that the fidelity of the cat state can be enhanced by improvements to and the perfection of the classical optical system. In quantum physics, superposition—illustrated by Schrödinger’s cat being both dead and alive—inspires ‘cat states’, utilized in quantum technologies. The authors propose a theory where the optical state, through multiple indirect atom interactions in an interferometric setup, can generate large-amplitude optical cat states, advancing quantum applications.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01617-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140802983","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 : 2024-04-25DOI: 10.1038/s42005-024-01621-w
Alexander Herbst, Timothé Estrampes, Henning Albers, Robin Corgier, Knut Stolzenberg, Sebastian Bode, Eric Charron, Ernst M. Rasel, Naceur Gaaloul, Dennis Schlippert
The sensitivity of atom interferometers depends on their ability to realize long pulse separation times and prevent loss of contrast by limiting the expansion of the atomic ensemble within the interferometer beam through matter-wave collimation. Here we investigate the impact of atomic interactions on collimation by applying a lensing protocol to a 39K Bose-Einstein condensate at different scattering lengths. Tailoring interactions, we measure energies corresponding to (340 ± 12) pK in one direction. Our results are supported by an accurate simulation, which allows us to extrapolate a 2D ballistic expansion energy of (438 ± 77) pK. Based on our findings we propose an advanced scenario, which enables 3D expansion energies below 16 pK by implementing an additional pulsed delta-kick. Our results pave the way to realize ensembles with more than 1 × 105 atoms and 3D energies in the two-digit pK range in typical dipole trap setups without the need for micro-gravity or long baseline environments. Precision measurements with atom interferometers benefit from reducing the expansion rate of the atomic ensemble within the interferometric beam through matter-wave collimation. Here we demonstrate a collimation method based on time-averaged optical potentials and tunable interactions, realizing expansion energies of a few hundred picokelvin.
{"title":"Matter-wave collimation to picokelvin energies with scattering length and potential shape control","authors":"Alexander Herbst, Timothé Estrampes, Henning Albers, Robin Corgier, Knut Stolzenberg, Sebastian Bode, Eric Charron, Ernst M. Rasel, Naceur Gaaloul, Dennis Schlippert","doi":"10.1038/s42005-024-01621-w","DOIUrl":"10.1038/s42005-024-01621-w","url":null,"abstract":"The sensitivity of atom interferometers depends on their ability to realize long pulse separation times and prevent loss of contrast by limiting the expansion of the atomic ensemble within the interferometer beam through matter-wave collimation. Here we investigate the impact of atomic interactions on collimation by applying a lensing protocol to a 39K Bose-Einstein condensate at different scattering lengths. Tailoring interactions, we measure energies corresponding to (340 ± 12) pK in one direction. Our results are supported by an accurate simulation, which allows us to extrapolate a 2D ballistic expansion energy of (438 ± 77) pK. Based on our findings we propose an advanced scenario, which enables 3D expansion energies below 16 pK by implementing an additional pulsed delta-kick. Our results pave the way to realize ensembles with more than 1 × 105 atoms and 3D energies in the two-digit pK range in typical dipole trap setups without the need for micro-gravity or long baseline environments. Precision measurements with atom interferometers benefit from reducing the expansion rate of the atomic ensemble within the interferometric beam through matter-wave collimation. Here we demonstrate a collimation method based on time-averaged optical potentials and tunable interactions, realizing expansion energies of a few hundred picokelvin.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01621-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140802848","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 : 2024-04-25DOI: 10.1038/s42005-024-01622-9
Valentina Martelli, Amaury Anquetil, Lin Al Atik, Julio Larrea Jiménez, Alaska Subedi, Ricardo P. S. M. Lobo, Kamran Behnia
The first-order phase transition between the liquid and gaseous phases ends at a critical point. Critical opalescence occurs at this singularity. Discovered in 1822, it is known to be driven by diverging fluctuations in the density. During the past two decades, boundaries between the gas-like and liquid-like regimes have been theoretically proposed and experimentally explored. Here, we show that fast cooling of near-critical sulfur hexafluoride (SF6), in presence of Earth’s gravity, favors dark opalescence, where visible photons are not merely scattered, but also absorbed. When the isochore fluid is quenched across the critical point, its optical transmittance drops by more than three orders of magnitude in the whole visible range, a feature which does not occur during slow cooling. We show that transmittance shows a dip at 2eV near the critical point, and the system can host excitons with binding energies ranging from 0.5 to 4 eV. The spinodal decomposition of the liquid-gas mixture, by inducing a periodical modulation of the fluid density, can provide a scenario to explain the emergence of this platform for coupling between light and matter. The possible formation of excitons and polaritons points to the irruption of quantum effects in a quintessentially classical context. The first-order phase boundary between the liquid and gaseous phases ends at a critical point where the fluid, kept at thermodynamic equilibrium, displays a turbidity known as ‘critical opalescence’. The authors quench a fluid across its critical point, find blackness instead of turbidity, and argue that, out of equilibrium, photons can be absorbed, not merely scattered.
{"title":"Near-critical dark opalescence in out-of-equilibrium SF6","authors":"Valentina Martelli, Amaury Anquetil, Lin Al Atik, Julio Larrea Jiménez, Alaska Subedi, Ricardo P. S. M. Lobo, Kamran Behnia","doi":"10.1038/s42005-024-01622-9","DOIUrl":"10.1038/s42005-024-01622-9","url":null,"abstract":"The first-order phase transition between the liquid and gaseous phases ends at a critical point. Critical opalescence occurs at this singularity. Discovered in 1822, it is known to be driven by diverging fluctuations in the density. During the past two decades, boundaries between the gas-like and liquid-like regimes have been theoretically proposed and experimentally explored. Here, we show that fast cooling of near-critical sulfur hexafluoride (SF6), in presence of Earth’s gravity, favors dark opalescence, where visible photons are not merely scattered, but also absorbed. When the isochore fluid is quenched across the critical point, its optical transmittance drops by more than three orders of magnitude in the whole visible range, a feature which does not occur during slow cooling. We show that transmittance shows a dip at 2eV near the critical point, and the system can host excitons with binding energies ranging from 0.5 to 4 eV. The spinodal decomposition of the liquid-gas mixture, by inducing a periodical modulation of the fluid density, can provide a scenario to explain the emergence of this platform for coupling between light and matter. The possible formation of excitons and polaritons points to the irruption of quantum effects in a quintessentially classical context. The first-order phase boundary between the liquid and gaseous phases ends at a critical point where the fluid, kept at thermodynamic equilibrium, displays a turbidity known as ‘critical opalescence’. The authors quench a fluid across its critical point, find blackness instead of turbidity, and argue that, out of equilibrium, photons can be absorbed, not merely scattered.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01622-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140732532","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}
Topological solitons, renowned for their stability and particle-like collision behaviors, have sparked interest in developing macroscopic-scale information processing devices. However, the exploration of interactions between multiple topological solitons in mechanical systems remains elusive. In this study, we construct a topological mechanical lattice supporting static vector solitons that represent quantized degrees of freedom and can freely propagate across the system. Drawing inspiration from coupled double atomic chains with sublattice symmetry breaking, we design a mechanical analogue featuring topologically protected boundary modes and induce independent modes to finite motions along branched motion pathways. Through a continuum theory, we describe the evolution of boundary modes with vector solitons composed of superposed kink solutions, identifying them as minimum energy pathways on the rugged effective potential surface with multiple degenerate ground states. Our results reveal the connection between transformable topological lattices and multistable systems, providing insight into nonlinear topological mechanics. Topological solitons can be realised in a range of platforms that have the potential for processing topologically protected information. Here, the authors identify a class of vector solitons in a mechanical lattice, showing superposed kinks and invertible polarizations, with implications for nonlinear topological mechanics.
{"title":"Static vector solitons in a topological mechanical lattice","authors":"Yuan Zhou, Yafei Zhang, Jiaxin Long, Aoxi Wang, Chang Qing Chen","doi":"10.1038/s42005-024-01630-9","DOIUrl":"10.1038/s42005-024-01630-9","url":null,"abstract":"Topological solitons, renowned for their stability and particle-like collision behaviors, have sparked interest in developing macroscopic-scale information processing devices. However, the exploration of interactions between multiple topological solitons in mechanical systems remains elusive. In this study, we construct a topological mechanical lattice supporting static vector solitons that represent quantized degrees of freedom and can freely propagate across the system. Drawing inspiration from coupled double atomic chains with sublattice symmetry breaking, we design a mechanical analogue featuring topologically protected boundary modes and induce independent modes to finite motions along branched motion pathways. Through a continuum theory, we describe the evolution of boundary modes with vector solitons composed of superposed kink solutions, identifying them as minimum energy pathways on the rugged effective potential surface with multiple degenerate ground states. Our results reveal the connection between transformable topological lattices and multistable systems, providing insight into nonlinear topological mechanics. Topological solitons can be realised in a range of platforms that have the potential for processing topologically protected information. Here, the authors identify a class of vector solitons in a mechanical lattice, showing superposed kinks and invertible polarizations, with implications for nonlinear topological mechanics.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01630-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140676460","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 : 2024-04-18DOI: 10.1038/s42005-024-01624-7
Yuting Wang, Gong-Bo Zhao, Kazuya Koyama, Will J. Percival, Ryuichi Takahashi, Chiaki Hikage, Héctor Gil-Marín, ChangHoon Hahn, Ruiyang Zhao, Weibing Zhang, Xiaoyong Mu, Yu Yu, Hong-Ming Zhu, Fei Ge
The reconstruction method was proposed more than a decade ago to boost the signal of baryonic acoustic oscillations measured in galaxy redshift surveys, which is one of key probes for dark energy. After moving the observed overdensities in galaxy surveys back to their initial position, the reconstructed density field is closer to a linear Gaussian field, with higher-order information moved back into the power spectrum. We find that by jointly analysing power spectra measured from the pre- and post-reconstructed galaxy samples, higher-order information beyond the 2-point power spectrum can be efficiently extracted, which generally yields an information gain upon the analysis using the pre- or post-reconstructed galaxy sample alone. This opens a window to easily use higher-order information when constraining cosmological models. Baryon Acoustic Oscillations (BAO) are formed in the early universe and can be measured galaxy redshift survey to probe dark energy, but this feature is degraded with galaxy structure evolution. The authors propose a method that simultaneously use pre- and post-reconstruction power spectra to extract higher order information for surveys to constrain cosmological models.
{"title":"Extracting high-order cosmological information in galaxy surveys with power spectra","authors":"Yuting Wang, Gong-Bo Zhao, Kazuya Koyama, Will J. Percival, Ryuichi Takahashi, Chiaki Hikage, Héctor Gil-Marín, ChangHoon Hahn, Ruiyang Zhao, Weibing Zhang, Xiaoyong Mu, Yu Yu, Hong-Ming Zhu, Fei Ge","doi":"10.1038/s42005-024-01624-7","DOIUrl":"10.1038/s42005-024-01624-7","url":null,"abstract":"The reconstruction method was proposed more than a decade ago to boost the signal of baryonic acoustic oscillations measured in galaxy redshift surveys, which is one of key probes for dark energy. After moving the observed overdensities in galaxy surveys back to their initial position, the reconstructed density field is closer to a linear Gaussian field, with higher-order information moved back into the power spectrum. We find that by jointly analysing power spectra measured from the pre- and post-reconstructed galaxy samples, higher-order information beyond the 2-point power spectrum can be efficiently extracted, which generally yields an information gain upon the analysis using the pre- or post-reconstructed galaxy sample alone. This opens a window to easily use higher-order information when constraining cosmological models. Baryon Acoustic Oscillations (BAO) are formed in the early universe and can be measured galaxy redshift survey to probe dark energy, but this feature is degraded with galaxy structure evolution. The authors propose a method that simultaneously use pre- and post-reconstruction power spectra to extract higher order information for surveys to constrain cosmological models.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01624-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140626612","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 : 2024-04-15DOI: 10.1038/s42005-024-01614-9
Juyi Li, Xiaoqun Wu, Jinhu Lü, Ling Lei
Evidence from both theoretical and empirical studies suggests that higher-order networks have emerged as powerful tools for modeling social contagions, such as opinion formation. In this article, we develop a model of social contagion on directed hypergraphs by considering the heterogeneity of individuals and environments in terms of reinforcing contagion effects. By distinguishing the directedness between nodes and hyperedges, we find that the bistable interval of the discontinuous phase transition decreases as the directedness strength decreases. Additionally, directed hypergraphs tend to generate bistable intervals when nodes with a large hyperdegree are more likely to adopt a specific opinion, as evidenced by simulations of directionality assignments for three sets of real networks. These findings provide two approaches to enhance the accuracy of predicting social contagion dynamics: one is to increase the stubbornness of all individuals, and the other is to prioritize increasing the stubbornness of highly influential individuals. Directed hypergraphs emerge as a potent framework for analyzing social contagion phenomena, incorporating the nuances of individual heterogeneity and the amplifying effects of environmental contagion reinforcement. The authors demonstrate that the interval of bistability within discontinuous phase transitions contracts with diminishing directedness strength
{"title":"Enhancing predictive accuracy in social contagion dynamics via directed hypergraph structures","authors":"Juyi Li, Xiaoqun Wu, Jinhu Lü, Ling Lei","doi":"10.1038/s42005-024-01614-9","DOIUrl":"10.1038/s42005-024-01614-9","url":null,"abstract":"Evidence from both theoretical and empirical studies suggests that higher-order networks have emerged as powerful tools for modeling social contagions, such as opinion formation. In this article, we develop a model of social contagion on directed hypergraphs by considering the heterogeneity of individuals and environments in terms of reinforcing contagion effects. By distinguishing the directedness between nodes and hyperedges, we find that the bistable interval of the discontinuous phase transition decreases as the directedness strength decreases. Additionally, directed hypergraphs tend to generate bistable intervals when nodes with a large hyperdegree are more likely to adopt a specific opinion, as evidenced by simulations of directionality assignments for three sets of real networks. These findings provide two approaches to enhance the accuracy of predicting social contagion dynamics: one is to increase the stubbornness of all individuals, and the other is to prioritize increasing the stubbornness of highly influential individuals. Directed hypergraphs emerge as a potent framework for analyzing social contagion phenomena, incorporating the nuances of individual heterogeneity and the amplifying effects of environmental contagion reinforcement. The authors demonstrate that the interval of bistability within discontinuous phase transitions contracts with diminishing directedness strength","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01614-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140556427","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 : 2024-04-15DOI: 10.1038/s42005-024-01606-9
Leon Lettermann, Alejandro Jurado, Timo Betz, Florentin Wörgötter, Sebastian Herzog
Building a representative model of a complex dynamical system from empirical evidence remains a highly challenging problem. Classically, these models are described by systems of differential equations that depend on parameters that need to be optimized by comparison with data. In this tutorial, we introduce the most common multi-parameter estimation techniques, highlighting their successes and limitations. We demonstrate how to use the adjoint method, which allows efficient handling of large systems with many unknown parameters, and present prototypical examples across several fields of physics. Our primary objective is to provide a practical introduction to adjoint optimization, catering for a broad audience of scientists and engineers. Multiple parameter estimation techniques are employed to empirically validate theoretical propositions regarding complex systems by discerning relevant free parameters from often scarce experimental data. In this tutorial, the authors provide a beginner’s guide to parameter estimation via adjoint optimization, and show its efficiency in prototypical problems across different fields of physics.
{"title":"Tutorial: a beginner’s guide to building a representative model of dynamical systems using the adjoint method","authors":"Leon Lettermann, Alejandro Jurado, Timo Betz, Florentin Wörgötter, Sebastian Herzog","doi":"10.1038/s42005-024-01606-9","DOIUrl":"10.1038/s42005-024-01606-9","url":null,"abstract":"Building a representative model of a complex dynamical system from empirical evidence remains a highly challenging problem. Classically, these models are described by systems of differential equations that depend on parameters that need to be optimized by comparison with data. In this tutorial, we introduce the most common multi-parameter estimation techniques, highlighting their successes and limitations. We demonstrate how to use the adjoint method, which allows efficient handling of large systems with many unknown parameters, and present prototypical examples across several fields of physics. Our primary objective is to provide a practical introduction to adjoint optimization, catering for a broad audience of scientists and engineers. Multiple parameter estimation techniques are employed to empirically validate theoretical propositions regarding complex systems by discerning relevant free parameters from often scarce experimental data. In this tutorial, the authors provide a beginner’s guide to parameter estimation via adjoint optimization, and show its efficiency in prototypical problems across different fields of physics.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01606-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140556418","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 : 2024-04-13DOI: 10.1038/s42005-024-01611-y
Vincenzo J. Pratley, Enej Caf, Miha Ravnik, Gareth P. Alexander
Active nematics are driven, non-equilibrium systems relevant to biological processes including tissue mechanics and morphogenesis, and to active metamaterials in general. We study the three-dimensional spontaneous flow transition of an active nematic in an infinite slab geometry using a combination of numerics and analytics. We show that it is determined by the interplay of two eigenmodes – called S- and D-mode – that are unstable at the same activity threshold and spontaneously breaks both rotational symmetry and chiral symmetry. The onset of the unstable modes is described by a non-Hermitian integro-differential operator, which we determine their exponential growth rates from using perturbation theory. The S-mode is the fastest growing. After it reaches a finite amplitude, the growth of the D-mode is anisotropic, being promoted perpendicular to the S-mode and suppressed parallel to it, forming a steady state with a full three-dimensional director field and a well-defined chirality. Lastly, we derive a model of the leading-order time evolution of the system close to the activity threshold. Active nematics are driven, non-equilibrium systems relevant to tissue mechanics and morphogenesis in biology, and with prospects as active metamaterials. The authors study the three-dimensional spontaneous flow transition with normal anchoring and show that it involves both chiral and rotational symmetry breaking, resulting in a fully three-dimensional flow with a twisted director field.
活性向列是与组织力学和形态发生等生物过程以及一般活性超材料相关的驱动型非平衡系统。我们采用数值和分析相结合的方法，研究了无限板几何中活性向列的三维自发流动转变。我们的研究表明，它是由两个特征模态（称为 S 模和 D 模）的相互作用决定的，这两个特征模态在相同的活性阈值下是不稳定的，并自发地打破了旋转对称性和手性对称性。不稳定模式的发生由一个非ermitian积分微分算子描述，我们利用扰动理论确定了它们的指数增长率。S 模式的增长速度最快。在达到有限振幅后，D 模式的增长是各向异性的，垂直于 S 模式的增长被促进，平行于 S 模式的增长被抑制，从而形成一个具有完整三维导演场和明确手性的稳态。最后，我们推导出系统在接近活动阈值时的前沿时间演化模型。活性线粒体是一种驱动型非平衡系统，与生物学中的组织力学和形态发生相关，并具有作为活性超材料的前景。作者研究了具有法向锚定的三维自发流动转变，结果表明它涉及手性和旋转对称性的破坏，导致具有扭曲导演场的全三维流动。
{"title":"Three-dimensional spontaneous flow transition in a homeotropic active nematic","authors":"Vincenzo J. Pratley, Enej Caf, Miha Ravnik, Gareth P. Alexander","doi":"10.1038/s42005-024-01611-y","DOIUrl":"10.1038/s42005-024-01611-y","url":null,"abstract":"Active nematics are driven, non-equilibrium systems relevant to biological processes including tissue mechanics and morphogenesis, and to active metamaterials in general. We study the three-dimensional spontaneous flow transition of an active nematic in an infinite slab geometry using a combination of numerics and analytics. We show that it is determined by the interplay of two eigenmodes – called S- and D-mode – that are unstable at the same activity threshold and spontaneously breaks both rotational symmetry and chiral symmetry. The onset of the unstable modes is described by a non-Hermitian integro-differential operator, which we determine their exponential growth rates from using perturbation theory. The S-mode is the fastest growing. After it reaches a finite amplitude, the growth of the D-mode is anisotropic, being promoted perpendicular to the S-mode and suppressed parallel to it, forming a steady state with a full three-dimensional director field and a well-defined chirality. Lastly, we derive a model of the leading-order time evolution of the system close to the activity threshold. Active nematics are driven, non-equilibrium systems relevant to tissue mechanics and morphogenesis in biology, and with prospects as active metamaterials. The authors study the three-dimensional spontaneous flow transition with normal anchoring and show that it involves both chiral and rotational symmetry breaking, resulting in a fully three-dimensional flow with a twisted director field.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01611-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140551127","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 : 2024-04-11DOI: 10.1038/s42005-024-01620-x
Jiayang Li, Qianni Zhang, Jiantao Wang, Andrew W. Poon
Silicon carbide (SiC) polytypes are emerging for integrated nonlinear and quantum photonics due to their wide-bandgap energies, second-order optic nonlinearity and process compatibility with complementary metal-oxide-semiconductor technologies. Among polytypes, 3C-SiC is the only one epitaxially grown on wafer-scale silicon substrates. However, on-chip nonlinear and quantum light sources leveraging the second-order nonlinearity of 3C-SiC have not been reported to our knowledge. Here, we design and fabricate an elliptical microring on 3C-SiC. We demonstrate a nonlinear light source with a second-harmonic generation efficiency of $$17.4pm 0.2 % {W}^{-1}$$ and difference-frequency generation with a signal-idler bandwidth of 97 nm. We demonstrate a spontaneous parametric down-conversion source with a photon-pair generation rate of 4.8 MHz and a coincidence-to-accidental ratio of $$3361pm 84$$ . We measure a low heralded single-photon second-order coherence $${g}_{H}^{left(2right)}=0.0007$$ . We observe time-bin entanglement with a visibility of $$86.0pm 2.4 %$$ using this source. Our work paves a way toward SiC-based on-chip nonlinear and quantum photonic circuits. Silicon carbide polytypes (SiC) exhibit second-order optic nonlinearity to act as on-chip nonlinear and quantum light sources, but their integration is typically challenging. The authors demonstrate the performance of 3C-SiC --a fully integrable polytype-- as an on-chip quantum light source based on its second-order susceptibility.
{"title":"An integrated 3C-silicon carbide-on-insulator photonic platform for nonlinear and quantum light sources","authors":"Jiayang Li, Qianni Zhang, Jiantao Wang, Andrew W. Poon","doi":"10.1038/s42005-024-01620-x","DOIUrl":"10.1038/s42005-024-01620-x","url":null,"abstract":"Silicon carbide (SiC) polytypes are emerging for integrated nonlinear and quantum photonics due to their wide-bandgap energies, second-order optic nonlinearity and process compatibility with complementary metal-oxide-semiconductor technologies. Among polytypes, 3C-SiC is the only one epitaxially grown on wafer-scale silicon substrates. However, on-chip nonlinear and quantum light sources leveraging the second-order nonlinearity of 3C-SiC have not been reported to our knowledge. Here, we design and fabricate an elliptical microring on 3C-SiC. We demonstrate a nonlinear light source with a second-harmonic generation efficiency of $$17.4pm 0.2 % {W}^{-1}$$ and difference-frequency generation with a signal-idler bandwidth of 97 nm. We demonstrate a spontaneous parametric down-conversion source with a photon-pair generation rate of 4.8 MHz and a coincidence-to-accidental ratio of $$3361pm 84$$ . We measure a low heralded single-photon second-order coherence $${g}_{H}^{left(2right)}=0.0007$$ . We observe time-bin entanglement with a visibility of $$86.0pm 2.4 %$$ using this source. Our work paves a way toward SiC-based on-chip nonlinear and quantum photonic circuits. Silicon carbide polytypes (SiC) exhibit second-order optic nonlinearity to act as on-chip nonlinear and quantum light sources, but their integration is typically challenging. The authors demonstrate the performance of 3C-SiC --a fully integrable polytype-- as an on-chip quantum light source based on its second-order susceptibility.","PeriodicalId":10540,"journal":{"name":"Communications Physics","volume":null,"pages":null},"PeriodicalIF":5.5,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s42005-024-01620-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140544586","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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