Reports on progress in physics. Physical Society (Great Britain)最新文献

{"title":"Searching for the QCD dark-matter axion.","authors":"Masha Baryakhtar, Leslie Rosenberg, Gray Rybka","doi":"10.1088/1361-6633/ae059d","DOIUrl":"10.1088/1361-6633/ae059d","url":null,"abstract":"<p><p>Proposed half a century ago, the quantum chromodynamics (QCD) axion explains the lack of charge and parity violation in the strong interactions and is a compelling candidate for cold dark matter. The last decade has seen the rapid improvement in the sensitivity and mass-range of axion experiments, as well as developments in theory regarding consequences of axion dark matter. We review here the astrophysical searches and theoretical progress regarding the QCD axion. We then give a historical overview of axion searches, review the current status and future prospects of dark matter axion searches, and then discuss proposed dark matter axion techniques currently in development.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145034849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Imaging nuclear shape through anisotropic and radial flow in high-energy heavy-ion collisions.","authors":"The Star Collaboration","doi":"10.1088/1361-6633/ae0fc3","DOIUrl":"10.1088/1361-6633/ae0fc3","url":null,"abstract":"<p><p>Most atomic nuclei exhibit ellipsoidal shapes characterized by quadrupole deformation<i>β</i>₂and triaxiality<i>γ</i>, and sometimes even a pear-like octupole deformation<i>β</i>₃. The STAR experiment introduced a new 'imaging-by-smashing' technique ((STAR Collaboration) 2024<i>Nature</i><b>635</b>67; Jia 2025<i>Rep. Prog. Phys.</i><b>88</b>092301) to image the nuclear global shape by colliding nuclei at ultra-relativistic speeds and analyzing outgoing debris. Features of nuclear shape manifest in collective observables like anisotropic flow<i>v_n</i>and radial flow via mean transverse momentum[pT]. We present new measurements of the variances of<i>v_n</i>(<i>n</i> = 2, 3, and 4) and[pT], and the covariance ofvn2with[pT], in collisions of highly deformed²³⁸U and nearly spherical¹⁹⁷Au. Ratios of these observables between the two systems effectively suppress common final-state effects, isolating the strong impact of uranium's deformation. By comparing results with state-of-the-art hydrodynamic model calculations, we extractβ2UandγUvalues consistent with those deduced from low-energy nuclear structure measurements. Measurements of<i>v</i>₃and its correlation with[pT]also provide the first experimental suggestion of a possible octupole deformation for²³⁸U. These findings provide significant support for using high-energy collisions to explore nuclear shapes on femtosecond timescales, with implications for both nuclear structure and quark-gluon plasma studies.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145240392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the fluctuations of the number of atoms in the condensate.","authors":"Maciej B Kruk, Piotr Kulik, Malthe F Andersen, Piotr Deuar, Mariusz Gajda, Krzysztof Pawłowski, Emilia Witkowska, Jan J Arlt, Kazimierz Rzążewski","doi":"10.1088/1361-6633/ae0e33","DOIUrl":"10.1088/1361-6633/ae0e33","url":null,"abstract":"<p><p>Bose-Einstein condensation (BEC) represents a remarkable phase transition, characterized by the formation of a single quantum subsystem. As a result, the statistical properties of the condensate are highly unique. In the case of a Bose gas, while the mean number of condensed atoms is independent of the choice of statistical ensemble, the microcanonical, canonical (CN), or grand CN (GC) variances differ significantly among these ensembles. In this paper, we review the progress made over the past 30 years in studying the statistical fluctuations of BECs. Focusing primarily on the ideal Bose gas, we emphasize the inequivalence of the Gibbs statistical ensembles and examine various approaches to this problem. These approaches include explicit analytic results for primarily one-dimensional systems, methods based on recurrence relations, asymptotic results for large numbers of particles, techniques derived from laser theory, and methods involving the construction of statistical ensembles via stochastic processes, such as the Metropolis algorithm. We also discuss the less thoroughly resolved problem of the statistical behavior of weakly interacting Bose gases. In particular, we elaborate on our stochastic approach, known as the hybrid sampling method. The experimental aspect of this field has gained renewed interest, especially following groundbreaking recent measurements of condensate fluctuations. These advancements were enabled by unprecedented control over the total number of atoms in each experimental realization. Additionally, we discuss the fluctuations in photonic condensates as an illustrative example of GC fluctuations. Finally, we briefly consider the future directions for research in the field of condensate statistics.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145208598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CaloChallenge 2022: A community challenge for fast calorimeter simulation.","authors":"Claudius G Krause, Michele Faucci Giannelli, Gregor Kasieczka, Benjamin Nachman, Dalila Salamani, David Shih, Anna Zaborowska, Oz Amram, Kerstin Borras, Matthew R Buckley, Erik Buhmann, Thorsten Buss, Renato Paulo Da Costa Cardoso, Anthony L Caterini, Nadezda Chernyavskaya, Federico A G Corchia, Jesse C Cresswell, Sascha Diefenbacher, Etienne Dreyer, Vijay Ekambaram, Engin Eren, Florian Ernst, Luigi Favaro, Matteo Franchini, Frank Gaede, Eilam Gross, Shih-Chieh Hsu, Kristina Jaruskova, Benno Käch, Jayant Kalagnanam, Raghav Kansal, Taewoo Kim, Dmitrii Kobylianskii, Anatolii Korol, William Korcari, Dirk Krücker, Katja Krüger, Marco Letizia, Shu Li, Qibin Liu, Xiulong Liu, Gabriel Loaiza-Ganem, Thandi Madula, Peter McKeown, Isabell-A Melzer-Pellmann, Vinicius Mikuni, Nam Nguyen, Ayodele Ore, Sofia Palacios Schweitzer, Ian Pang, Kevin Pedro, Tilman Plehn, Witold Pokorski, Huilin Qu, Piyush Raikwar, John Andrew Raine, Humberto Reyes-González, Lorenzo Rinaldi, Brendan Leigh Ross, Moritz Alfons Wilhelm Alfons Wilhelm Scham, Simon Schnake, Chase Shimmin, Eli Shlizerman, Nathalie Soybelman, Mudhakar Srivatsa, Kalliopi Tsolaki, Sofia Vallecorsa, Kyongmin Yeo, Rui Zhang","doi":"10.1088/1361-6633/ae1304","DOIUrl":"https://doi.org/10.1088/1361-6633/ae1304","url":null,"abstract":"<p><p>We present the results of the ``Fast Calorimeter Simulation Challenge 2022'' --- the CaloChallenge. We study state-of-the-art generative models on four calorimeter shower datasets of increasing dimensionality, ranging from a few hundred voxels to a few tens of thousand voxels. The 31 individual submissions span a wide range of current popular generative architectures, including Variational AutoEncoders (VAEs), Generative Adversarial Networks (GANs), Normalizing Flows, Diffusion models, and models based on Conditional Flow Matching. We compare all submissions in terms of quality of generated calorimeter showers, as well as shower generation time and model size. To assess the quality we use a broad range of different metrics including differences in 1-dimensional histograms of observables, KPD/FPD scores, AUCs of binary classifiers, and the log-posterior of a multiclass classifier. The results of the CaloChallenge provide the most complete and comprehensive survey of cutting-edge approaches to calorimeter fast simulation to date. In addition, our work provides a uniquely detailed perspective on the important problem of how to evaluate generative models. As such, the results presented here should be applicable for other domains that use generative AI and require fast and faithful generation of samples in a large phase space.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145294553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physics of droplet regulation in biological cells.","authors":"David Zwicker, Oliver Paulin, Cathelijne Ter Burg","doi":"10.1088/1361-6633/ae12a7","DOIUrl":"https://doi.org/10.1088/1361-6633/ae12a7","url":null,"abstract":"<p><p>Droplet formation has emerged as an essential concept for the spatiotemporal organisation of biomolecules in cells. However, classical descriptions of droplet dynamics based on passive liquid-liquid phase separation cannot capture the complex situation inside cells. This review discusses three distinct aspects that are crucial in cells: (i) biomolecules are diverse and individually complex, implying that cellular droplets posses complex internal behaviour, e.g., in terms of their material properties; (ii) the cellular environment contains many solid-like structures that droplets can wet; (iii) cells are alive and use fuel to drive processes out of equilibrium. We illustrate how these principles control droplet nucleation, growth, position, and count to unveil possible regulatory mechanisms in biological cells and other applications of phase separation.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145287853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic and geometric shifts in wave scattering.","authors":"Konstantin Y Bliokh, Zeyu Kuang, Stefan Rotter","doi":"10.1088/1361-6633/ae0bac","DOIUrl":"10.1088/1361-6633/ae0bac","url":null,"abstract":"<p><p>Since Berry's pioneering 1984 work, the separation of<i>geometric</i>and<i>dynamic</i>contributions in the<i>phase</i>of an evolving wave has become fundamental in physics, underpinning diverse phenomena in quantum mechanics, optics, and condensed matter. Here we extend this geometric-dynamic decomposition from the wave-evolution phase to a distinct class of<i>wave scattering</i>problems, where observables (such as frequency, momentum, or position) experience<i>shifts in their expectation values</i>between the input and output wave states. We describe this class of problems using a unitary scattering matrix and the associated<i>generalized Wigner-Smith operator</i>(GWSO), which involves gradients of the scattering matrix with respect to conjugate variables (time, position, or momentum, respectively). We show that both the GWSO and the resulting expectation-values shifts admit gauge-invariant decompositions into dynamic and geometric parts, related respectively to gradients of the<i>eigenvalues</i>and<i>eigenvectors</i>of the scattering matrix. We illustrate this general theory through a series of examples, including frequency shifts in polarized-light transmission through a time-varying waveplate (linked to the Pancharatnam-Berry phase), momentum shifts at spatially varying metasurfaces, optical forces, beam shifts upon reflection at a dielectric interface, and Wigner time delays in 1D scattering. This unifying framework illuminates the interplay between geometry and dynamics in wave scattering and can be applied to a broad range of physical systems.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145151736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is triboelectricity confusing, confused or complex?","authors":"Karl P Olson, Laurence D Marks","doi":"10.1088/1361-6633/ae08cb","DOIUrl":"10.1088/1361-6633/ae08cb","url":null,"abstract":"<p><p>In this report, we look at the fundamental physics of triboelectricity, charge transfer due to contact and sliding. While much of the report focuses upon recent advances such as the incorporation of flexoelectric contributions, we also include older work, some from centuries ago, which can only now be fully understood. Basic concepts and theories ranging from elements of tribology and contact mechanics through semiconductor built-in potentials, electromechanical terms, mechanochemistry and trap states are briefly described, linking to established surface science and interface physics. We then overview the main models that have been proposed, showing that they all fall within conventional electrostatics combined with other established science. We conclude with some suggestions for the future. Based upon this overview, our conclusion is that triboelectricity is a slightly complex combination of classic tribology and standard electrostatic phenomena that can be understood using the generalized Ampère's law connecting the electric displacement field with both Coulomb and polarization contributions, and the free carrier density, that is∇⋅D=ρf. Triboelectricity may be confusing, it is not really confused if care is taken, but it is complex.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145088476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topological phases in discrete stochastic systems.","authors":"Jaime Agudo-Canalejo, Evelyn Tang","doi":"10.1088/1361-6633/ae07fd","DOIUrl":"10.1088/1361-6633/ae07fd","url":null,"abstract":"<p><p>Topological invariants have proved useful for analyzing emergent function as they characterize a property of the entire system, and are insensitive to local details, disorder, and noise. They support boundary states, which reduce the system response to a lower dimensional space and, in two-dimensional (2D) systems, offer a mechanism for the emergence of global cycles within a large phase space. Topological invariants have been heavily studied in quantum electronic systems and have been observed in other classical platforms such as mechanical lattices. However, this framework largely describes equilibrium systems within an ordered crystalline lattice, whereas biological systems are often strongly non-equilibrium with stochastic components. We review recent developments in topological states in discrete stochastic models in one-dimensional and 2D systems, and initial progress in identifying testable signatures of topological states in molecular systems and ecology. These models further provide simple principles for targeted dynamics in synthetic systems and in the engineering of reconfigurable materials. Lastly, we describe novel theoretical properties of these systems such as the necessity for non-Hermiticity in permitting edge states, as well as new analytical tools to reveal these properties. The emerging developments shed light on fundamental principles for non-equilibrium systems and topological protection enabling robust biological function.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145082619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantum metrology with a continuous-variable system.","authors":"Matteo Fadel, Noah Roux, Manuel Gessner","doi":"10.1088/1361-6633/ae00d8","DOIUrl":"10.1088/1361-6633/ae00d8","url":null,"abstract":"<p><p>As one of the main pillars of quantum technologies, quantum metrology aims to improve measurement precision using techniques from quantum information. The two main strategies to achieve this are the preparation of nonclassical states and the design of optimized measurement observables. We discuss precision limits and optimal strategies in quantum metrology and sensing with a single mode of quantum continuous variables. We focus on the practically most relevant cases of estimating displacements and rotations and provide the sensitivities of the most important classes of states that includes Gaussian states and superpositions of Fock states or coherent states. Fundamental precision limits that are obtained from the quantum Fisher information are compared to the precision of a simple moment-based estimation strategy based on the data obtained from possibly sub-optimal measurement observables, including homodyne, photon number, parity and higher moments. Finally, we summarize some of the main experimental achievements and present emerging platforms for continuous-variable sensing. These results are of particular interest for experiments with quantum light, trapped ions, mechanical oscillators, and microwave resonators.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144981875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A universal constraint for relaxation rates for quantum Markov generators: complete positivity and beyond<sup />.","authors":"Dariusz Chruściński, Frederik Vom Ende, Gen Kimura, Paolo Muratore-Ginanneschi","doi":"10.1088/1361-6633/ae075f","DOIUrl":"10.1088/1361-6633/ae075f","url":null,"abstract":"<p><p>Relaxation rates are key characteristics of quantum processes, as they determine how quickly a quantum system thermalizes, equilibrates, decoheres, and dissipates. While they play a crucial role in theoretical analyses, relaxation rates are also often directly accessible through experimental measurements. Recently, it was shown that for quantum processes governed by Markovian semigroups, the relaxation rates satisfy a universal constraint: the maximal rate is upper-bounded by the sum of all rates divided by the dimension of the Hilbert space. This bound, initially conjectured a few years ago, was only recently proven using classical Lyapunov theory. In this work, we present a new, purely algebraic proof of this constraint. Remarkably, our approach is not only more direct but also allows for a natural generalization beyond completely positive semigroups. We show that complete positivity can be relaxed to two-positivity without affecting the validity of the constraint. This reveals that the bound is more subtle than previously understood: two-positivity is necessary, but even when further relaxed to Schwarz maps, a slightly weaker-yet still non-trivial-universal constraint still holds. Finally, we explore the connection between these bounds and the number of steady states in quantum processes, uncovering a deeper structure underlying their behavior.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145076831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}