物理最新文献

{"title":"Quantum correlations of the photon fields in a waveguide quantum electrodynamics","authors":"Ya. S. Greenberg,&nbsp;O. A. Chuikin,&nbsp;A. G. Moiseev,&nbsp;A. A. Shtygashev,&nbsp;O. V. Kibis","doi":"10.1140/epjb/s10051-025-01020-2","DOIUrl":"10.1140/epjb/s10051-025-01020-2","url":null,"abstract":"<div><p>We present a time-dependent quantum calculations of the first-order and second-order photon correlation functions for the scattering of a single-photon pulse on a two-level atom (qubit) embedded in a one-dimensional open waveguide. Within Markov approximation we find the analytic expression for the quantum operator of positive frequency electric field. We restricted Hilbert space of initial states by the states with one and two excitations and show that the photon probability amplitudes are given by the off-diagonal matrix elements of the electric field operator between these states. For two-excitation initial state where the atom is excited and there exists a single photon in a waveguide we calculate the second-order correlation function which describes the measurements by two detectors at two different space-time points. The second-order correlation function exhibits the interference term showing that the measurements of two detectors are correlated. This interference is similar to that found in the Hanbury Brown and Twiss correlation experiment with two indistinguishable photons.</p></div>","PeriodicalId":787,"journal":{"name":"The European Physical Journal B","volume":"98 8","pages":""},"PeriodicalIF":1.7,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Basis-independent coherence in noninertial frames","authors":"Ming-Ming Du,&nbsp;Yi-Hao Fan,&nbsp;Hong-Wei Li,&nbsp;Shu-Ting Shen,&nbsp;Xiao-Jing Yan,&nbsp;Xi-Yun Li,&nbsp;Wei Zhong,&nbsp;Yu-Bo Sheng,&nbsp;Lan Zhou","doi":"10.1140/epjc/s10052-025-14588-x","DOIUrl":"10.1140/epjc/s10052-025-14588-x","url":null,"abstract":"<div><p>We investigate the behavior of basis-independent quantum coherence between two modes of a free Dirac field as observed by relatively accelerated observers. Our findings reveal three key results: (i) the basis-independent coherence between modes <span>(A)</span> and <span>(B_{I})</span> decreases with increasing acceleration but remains finite even in the limit of infinite acceleration; (ii) at zero acceleration, the coherence between modes <span>(A)</span> and <span>(B_{II})</span> is nonzero-contrasting with the behavior of basis-dependent coherence, which typically vanishes in this case; and (iii) the basis-independent coherence between modes <span>(B_I)</span> and <span>(B_{II})</span> remains constant regardless of acceleration, exhibiting a freezing phenomenon. These results demonstrate the intrinsic robustness of basis-independent coherence under Unruh effects.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 8","pages":""},"PeriodicalIF":4.8,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14588-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144843317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Probing protein–protein interactions with drag flow: a case study of F-actin and tropomyosin","authors":"Camille Bagès,&nbsp;Morgan Chabanon,&nbsp;Wouter Kools,&nbsp;Thomas Dos Santos,&nbsp;Rebecca Pagès,&nbsp;Maria Elena Sirkia,&nbsp;Cécile Leduc,&nbsp;Anne Houdusse,&nbsp;Antoine Jégou,&nbsp;Guillaume Romet-Lemonne,&nbsp;Hugo Wioland","doi":"10.1140/epje/s10189-025-00509-z","DOIUrl":"10.1140/epje/s10189-025-00509-z","url":null,"abstract":"<p>Tropomyosins are central regulators of the actin cytoskeleton, controlling the binding and activity of the other actin binding proteins. The interaction between tropomyosin and actin is quite unique: single tropomyosin dimers bind weakly to actin filaments but get stabilised by end-to-end attachment with neighbouring tropomyosin dimers, forming clusters which wrap around the filament. Force spectroscopy is a powerful approach for studying protein–protein interactions, but classical methods which usually pull with pN forces on a single protein pair, are not well adapted to tropomyosins. Here, we propose a method in which a hydrodynamic drag force is applied directly to the proteins of interest, by imposing a controlled fluid flow inside a microfluidic chamber. The breaking of the protein bonds is directly visualised with fluorescence microscopy. Using this approach, we reveal that very low forces from 0.01 to 0.1 pN per tropomyosin dimer trigger the detachment of entire tropomyosin clusters from actin filaments. We show that the tropomyosin cluster detachment rate depends on the cytoplasmic tropomyosin isoform (Tpm1.6, 1.7, 1.8) and increases exponentially with the applied force. These observations lead us to propose a cluster detachment model which suggests that tropomyosins dynamically explore different positions over the actin filament. Our experimental setup can be used with many other cytoskeletal proteins, and we show, as a proof-of-concept, that the velocity of myosin-X motors is reduced by an opposing fluid flow. Overall, this method expands the range of protein–protein interactions that can be studied by force spectroscopy.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"48 8-9","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance analysis of the radiative Reiner–Philippoff hybrid nanofluid flow over a stretching(/)shrinking sheet under the effect of suction","authors":"Ashish Mishra","doi":"10.1007/s12043-025-02952-1","DOIUrl":"10.1007/s12043-025-02952-1","url":null,"abstract":"<div><p>The primary aim of the present paper is to analyse the Reiner–Philippoff hybrid nanofluid <b>(</b>HNF<b>)</b> flow over a stretching<span>(/)</span>shrinking sheet under the influence of thermal radiation and suction. A set of partial differential equations is used to describe the model, which is then reduced to non-dimensional ordinary differential equations through similarity transformations and solved computationally with the help of the bvp4c function. A graphical investigation examines the effects of various parameters, including the magnetic parameter, suction, Philippoff fluid parameter, Eckert number, radiation parameter, porosity parameter and Bingham number on velocity, temperature, skin friction and the local Nusselt number. The results show that as the Bingham number, Philippoff fluid parameter and stretching<span>(/)</span>shrinking parameter increase, the velocity profiles exhibit an upward trend. In addition, increasing the magnetic, porosity and suction parameters leads to higher absolute values of the skin friction coefficient. It is also noted that the rate of heat transfer increases up to 14.11% with an increase in the radiation parameter. The novel findings of this study provide a deeper understanding of HNF behaviour, which can facilitate the optimisation of heat transfer systems in industrial and engineering applications.</p></div>","PeriodicalId":743,"journal":{"name":"Pramana","volume":"99 3","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the motion of classical and quantum complex scalar waves in non-homogeneous media","authors":"Traian Popescu","doi":"10.1140/epjp/s13360-025-06699-x","DOIUrl":"10.1140/epjp/s13360-025-06699-x","url":null,"abstract":"<div><p>The present paper concerns a formalism aimed to describe the behavior and trajectories of complex scalar waves with space-varying amplitude in media characterized by variable refractive index. The classical wave equation is transformed into an eikonal-type equation, without imposing the geometrical optics limit, satisfied by an effective refractive index. The effective index combines the refractive properties of the medium with self-refraction phenomena generated by the space dependence of the wave amplitude. It also induces wave packet dispersion, leading to relations between the group and phase velocities that are particularly relevant in the context of <i>de Broglie</i> waves. The equations of motion are provided, and it is shown that the self-refraction term bends the trajectory of the wave and changes its velocity. The dynamics is dictated by the curvature of the trajectory expressed in terms of the gradient of the effective refractive index. The uncovered findings point toward a possible generalization of geometrical optics with relevant implications for its relation to quantum mechanics, general relativity and transformation optics.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjp/s13360-025-06699-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}

{"title":"Influence of anisotropy in permeability on Couette–Poiseuille flow of micropolar fluid through an annular anisotropic porous medium","authors":"Amit Kumar,&nbsp;Krishna Prasad Madasu","doi":"10.1140/epjp/s13360-025-06692-4","DOIUrl":"10.1140/epjp/s13360-025-06692-4","url":null,"abstract":"<div><p>In the present work, we have examined the anisotropic effect of permeability on micropolar fluid flow through the annular space between two coaxial cylinders filled with a porous medium. The key anisotropic parameters (permeability ratio and anisotropic angle) are crucial in characterizing the flow in an anisotropic porous medium. The combined action of the applied pressure gradient and the movement of the outer cylinder in an axial direction leads to the development of flow in an annular porous space. In this support, the no-slip boundary conditions at the outer cylinder are assumed. Both velocity and microrotation slip conditions are applied at the inner cylinder, enhancing the practicality and real-world applicability of the study. The graphical representation of velocity, microrotation, and shear stress profiles for variation in permeability ratio, anisotropic angle, Darcy number, micropolar and slip parameters are presented and discussed. The finding shows that velocity and microrotation vectors are strongly affected when the permeability ratio and anisotropic angle vary, and so does the shear distribution. However, the influence of anisotropy decreases as the Darcy number rises. Slip conditions help to enhance velocity and microrotation. The present study’s results have excellent applications in designing artificial nanoporous materials of annular shape, which are used for various industrial purposes, such as in filtration plants, heat storage, and other engineering fields.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-gravitating nonlinear Dirac fields","authors":"Huan Zhang,&nbsp;Jingsong He","doi":"10.1140/epjc/s10052-025-14609-9","DOIUrl":"10.1140/epjc/s10052-025-14609-9","url":null,"abstract":"<div><p>We consider the self-gravitating Dirac field with a scalar fermion self-interaction term. For strong enough attractive fermion self-interaction, the maximum Arnowitt–Deser–Misner mass of soliton solutions consisting of two fermions can exceed the limit of noninteracting Dirac stars classically, and the “particle-like” solutions of the system can exhibit multiplicity, multiple valid solutions for a single set of parameters, that is inherent in the nonlinear Dirac field. We also find the mass-scale separation in our system similar to that discussed in the Einstein–Dirac–Higgs system. Interestingly, the system admits parity-violated solutions. The broken parity symmetry can be restored by increasing the central redshift of the solution.\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 8","pages":""},"PeriodicalIF":4.8,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14609-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}

{"title":"Painlevé analysis, conservation laws and exact solutions of the fourth-order nonlinear Schrödinger equation","authors":"Nikolay A. Kudryashov,&nbsp;Chao-Qing Dai,&nbsp;Qin Zhou,&nbsp;Daniil R. Nifontov","doi":"10.1140/epjp/s13360-025-06693-3","DOIUrl":"10.1140/epjp/s13360-025-06693-3","url":null,"abstract":"<div><p>The fourth-order nonlinear Schrödinger equation for describing optical solitons is studied. The Painlevé test for nonlinear partial differential equations is used to study integrability properties of equation. It is shown that the equation does not pass the Painlevé test and consequently the Cauchy problem cannot be solved by the inverse scattering transform. A condition is found for the parameter value of the equation at which an analytical solution is possible in traveling wave variables. Using direct algebraic transformations of the system of equations, three independent conservation laws are constructed for the equation under study. The first integrals of the reduction to the nonlinear ordinary differential equation are obtained from the conservation laws. Optical solitons described by the partial differential equation are found under additional conditions on the parameters of the equation. Conserved densities corresponding to the power, linear momentum, and energy of optical solitons are calculated.</p></div>","PeriodicalId":792,"journal":{"name":"The European Physical Journal Plus","volume":"140 8","pages":""},"PeriodicalIF":2.9,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reinforcement learning of a biflagellate model microswimmer","authors":"Sridhar Bulusu,&nbsp;Andreas Zöttl","doi":"10.1140/epje/s10189-025-00513-3","DOIUrl":"10.1140/epje/s10189-025-00513-3","url":null,"abstract":"<p>Many microswimmers are able to swim through viscous fluids by employing periodic non-reciprocal deformations of their appendages. Here we use a simple microswimmer model inspired by swimming biflagellates which consists of a spherical cell body and two small spherical beads representing the motion of the two flagella. Using reinforcement learning, we identify for different microswimmer morphologies quasi-optimized swimming strokes. For all studied cases, the identified strokes result in symmetric and quasi-synchronized beating of the two flagella beads. Interestingly, the stroke-averaged flow fields are of pusher type, and the observed swimming gaits outperform previously used biflagellate microswimmer models relying on predefined circular flagella-bead motion.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"48 8-9","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-025-00513-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}

{"title":"Measurement of the atmospheric (nu _{mu }) flux with six detection units of KM3NeT/ORCA","authors":"KM3NeT Collaboration","doi":"10.1140/epjc/s10052-025-14513-2","DOIUrl":"10.1140/epjc/s10052-025-14513-2","url":null,"abstract":"<div><p>A measurement of the atmospheric <span>(nu _{mu }+bar{nu }_{mu })</span> flux with energies between 1 and 100 GeV is presented. The measurement has been performed using data taken with the first six detection units of the KM3NeT/ORCA detector, referred to as ORCA6. The data were collected between January 2020 and November 2021 and correspond to 510 days of livetime, with a total exposure of 433 kton<span>(cdot )</span>years. Using machine learning classification, 3894 neutrino candidate events have been selected with an atmospheric muon contamination of less than 1<span>(%)</span>. The atmospheric <span>(nu _{mu }+bar{nu }_{mu })</span> energy spectrum is derived using an unfolding procedure and the impact of systematic uncertainties is estimated. The atmospheric <span>(nu _{mu }+bar{nu }_{mu })</span> flux measured using the ORCA6 configuration is in agreement with the values measured by other experiments. \u0000\u0000</p></div>","PeriodicalId":788,"journal":{"name":"The European Physical Journal C","volume":"85 8","pages":""},"PeriodicalIF":4.8,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epjc/s10052-025-14513-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}