We develop a framework for the stochastic thermodynamics of a probe coupled to a fluctuating medium with spatio-temporal correlations, described by a scalar field. For a Brownian particle dragged by a harmonic trap through a fluctuating Gaussian field, we show that near criticality (where the field displays long-range spatial correlations) the spatially-resolved average heat flux develops a dipolar structure, where heat is absorbed in front and dissipated behind the dragged particle. Moreover, a perturbative calculation reveals that the dissipated power displays three distinct dynamical regimes depending on the drag velocity.
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ISSN: 1286-4854
A Letters journal serving all areas of physics and its related fields, EPL publishes the highest quality research from around the world, and provides authors with fast, fair and constructive peer review thanks to an Editorial Board of active scientists, who are experts in their respective fields.
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Davide Venturelli et al 2024 EPL 146 27001
P. A. Varotsos et al 2024 EPL 146 22001
Upon employing the new concept of time, termed natural time, the analysis of seismicity reveals that, before major earthquakes, the variations of the Earth's electric and/or magnetic field are accompanied by increase of the fluctuations of the entropy change of seismicity under time reversal as well as by decrease of the fluctuations of the seismicity order parameter. Hence, natural time analysis reveals that before major earthquakes independent datasets of different geophysical observables (seismicity, Earth's magnetic and/or electric field) exhibit changes, which are observed simultaneously.
To the memory of the Academician Seiya Uyeda.
Dongwook Go et al 2021 EPL 135 37001
In solids, electronic Bloch states are formed by atomic orbitals. While it is natural to expect that orbital composition and information about Bloch states can be manipulated and transported, in analogy to the spin degree of freedom extensively studied in past decades, it has been assumed that orbital quenching by the crystal field prevents significant dynamics of orbital degrees of freedom. However, recent studies reveal that an orbital current, given by the flow of electrons with a finite orbital angular momentum, can be electrically generated and transported in wide classes of materials despite the effect of orbital quenching in the ground state. Orbital currents also play a fundamental role in the mechanisms of other transport phenomena such as spin Hall effect and valley Hall effect. Most importantly, it has been proposed that orbital currents can be used to induce magnetization dynamics, which is one of the most pivotal and explored aspects of magnetism. Here, we give an overview of recent progress and the current status of research on orbital currents. We review proposed physical mechanisms for generating orbital currents and discuss candidate materials where orbital currents are manifest. We review recent experiments on orbital current generation and transport and discuss various experimental methods to quantify this elusive object at the heart of orbitronics —an area which exploits the orbital degree of freedom as an information carrier in solid-state devices.
Dun Han and Xiang Li 2024 EPL 146 21002
Conventional models of decision-making are predicated upon the notion of rational deliberation. However, empirical evidence has increasingly highlighted the pervasive role of bounded rationality in shaping decisional outcomes. The manifestation of bounded rationality is evident through a spectrum of cognitive biases and heuristics, including but not limited to anchoring, availability, the decoy effect, herd behavior, and the nuanced dynamics of reward and punishment, as well as the implications of weighting and framing effects. This prospective study is dedicated to a comprehensive exploration of such multiple factors together with their impacts to the architecture and functionality of decision-making processes, and their further research potentials as well.
Min Liu et al 2024 EPL 146 21001
Network resilience measures complex systems' ability to adjust its activity to retain the basic functionality for systematic errors or failures, which has attracted increasingly attention from various fields. Resilience analyses play an important role for early warning, prediction, and proposing potential strategies or designing optimal resilience systems. This letter reviews the advanced progress of network resilience from three aspects: Resilience measurement, resilience analysis, as well as resilience recovery strategies. We outline the challenges of network resilience which should be investigated in the future.
Francisco A. Rodrigues 2023 EPL 144 22001
Machine learning is a rapidly growing field with the potential to revolutionize many areas of science, including physics. This review provides a brief overview of machine learning in physics, covering the main concepts of supervised, unsupervised, and reinforcement learning, as well as more specialized topics such as causal inference, symbolic regression, and deep learning. We present some of the principal applications of machine learning in physics and discuss the associated challenges and perspectives.
Charles Andrew Downing and Muhammad Shoufie Ukhtary 2024 EPL 146 10001
The challenge of storing energy efficiently and sustainably is highly prominent within modern scientific investigations. Due to the ongoing trend of miniaturization, the design of expressly quantum storage devices is itself a crucial task within current quantum technological research. Here we provide a transparent analytic model of a two-component quantum battery, composed of a charger and an energy holder, which is driven by a short laser pulse. We provide simple expressions for the energy stored in the battery, the maximum amount of work which can be extracted, both the instantaneous and the average powers, and the relevant charging times. This allows us to discuss explicitly the optimal design of the battery in terms of the driving strength of the pulse, the coupling between the charger and the holder, and the inevitable energy loss into the environment. We anticipate that our theory can act as a helpful guide for the nascent experimental work building and characterizing the first generation of truly quantum batteries.
Sauro Succi et al 2023 EPL 144 10001
We present a pedagogical introduction to the current state of quantum computing algorithms for the simulation of classical fluids. Different strategies, along with their potential merits and liabilities, are discussed and commented on.
Benno Liebchen and Demian Levis 2022 EPL 139 67001
Chiral active matter comprises particles which can self-propel and self-rotate. Examples range from sperm cells and bacteria near walls to autophoretic L-shaped colloids. In this perspective article we focus on recent developments in chiral active matter. After briefly discussing the motion of single particles, we discuss collective phenomena ranging from vortex arrays and patterns made of rotating micro-flocks to states featuring unusual rheological properties.
Colin Benjamin and Ritesh Das 2024 EPL 146 16006
We propose a set of thermoelectric experiments based on Aharonov-Bohm interferometry to probe Majorana bound states (MBS), which are generated in 2D topological insulators (TI) in the presence of superconducting and ferromagnetic correlations via the proximity effect. The existence and nature (coupled or uncoupled) of these MBS can be determined by studying the charge and heat transport, specifically, the behavior of various thermoelectric coefficients like the Seebeck coefficient, Peltier coefficient, thermal conductance, and violations of Wiedemann-Franz law as a function of the Fermi energy and Aharonov-Bohm flux piercing the TI ring with the embedded MBS.
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S. Layek et al 2024 EPL 146 46002
The lattice dynamics of the superconducting materials LaFeSiH and LaFeSiO1-δ as well as their intermetallic precursor LaFeSi are investigated by polarized Raman spectroscopy and first-principles calculations, together with X-ray and advanced electron diffraction techniques for their structural analysis. We find that the Fe-dominated Raman-active modes reflect the chemical peculiarities of these silicides compared to their pnictide counterparts, with enhanced structural couplings between the FeSi layer and the spacer that can be related to the ionic vs. covalent character of the latter. In addition, we find signatures of enhanced electron-phonon coupling for some of the Raman-active modes. Beyond that, our study reveals intriguing Fe-based Raman features as well as structural subtleties in LaFeSiH suggesting that this superconductor may formally be non-centrosymmetric.
Mladen Kovačević et al 2024 EPL 146 42002
We revisit the familiar scenario involving two parties in relative motion, in which Alice stays at rest while Bob goes on a journey at speed βc along an arbitrary trajectory and reunites with Alice after a certain period of time. It is a well-known consequence of special relativity that the time that passes until they meet again is different for the two parties and is shorter in Bob's frame by a factor of . We investigate how this asymmetry manifests itself from an information-theoretic viewpoint. Assuming that Alice and Bob transmit signals of equal average power to each other during the whole journey, and that additive white Gaussian noise is present at both sides, we show that the maximum number of bits per second that Alice can transmit reliably to Bob is always higher than the one Bob can transmit to Alice. Equivalently, the energy per bit invested by Alice is lower than that invested by Bob, meaning that the traveler is less efficient from the communication perspective, as conjectured by Jarett and Cover.
Andrés G. Jirón et al 2024 EPL 146 40001
The problem of vectorial mesons embedded in an electromagnetic field via Duffin-Kemmer-Petiau (DKP) formalism is reinvestigated. Considering the electromagnetic interaction as a minimal coupling, an incorrect value is identified for the gyromagnetic factor (g-factor). Furthermore, it is shown that it is cumbersome to find analytical solutions due to the presence of the so-called anomalous term for the spin-1 sector of the DKP theory. Suspecting that the anomalous term results from an incomplete version of the DKP equation to describe the electromagnetic interaction, we consider the addition of a non-minimal coupling. This leads to the correct g-factor and, as a consequence, the anomalous term becomes proportional to an external four current. As an application, the DKP equation with a static uniform magnetic field is considered, yielding the corresponding Landau levels.
Qi Gao et al 2024 EPL 146 31001
We analyze the static response to kinetic perturbations of nonequilibrium steady states that can be modeled as diffusions. We demonstrate that kinetic response is purely a nonequilibirum effect, measuring the degree to which the Fluctuation-Dissipation Theorem is violated out of equilibrium. For driven diffusions in a flat landscape, we further demonstrate that such response is constrained by the strength of the nonequilibrium driving via quantitative inequalities.
Chandrashekar Radhakrishnan et al 2024 EPL 146 38001
Protecting entanglement from decoherence is a critical aspect of quantum information processsing. For many-body quantum systems evolving under decoherence, estimating multipartite entanglement is challenging. This challenge can be met up by considering a distance-based measure such as relative entropy of entanglement which decisively measures entanglement in both pure as well as mixed states. In this work, we investigate the tripartite entanglement dynamics of pure and mixed states in the presence of a structured dephasing environment at finite temperature. We show that the robustness of the quantum system to decoherence is dependent on the distribution of entanglement and its relation to different configurations of the bath. If the bath is structured individually such that each qubit has its own environment, the system has different dynamics compared to when the bath is common to all the three qubits. From the results we conjecture that there is a connection between the distribution of entanglement among the qubits and the distribution of bath degrees of freedom, and the interplay of these two distributions determines the decay rate of the entanglement dynamics. The sustainability of tripartite entanglement is shown to be enhanced significantly in the presence of reservoir memory.
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Klimchitskaya et al
The Casimir force caused by the electromagnetic fluctuations
is computed in the configurations of micro- and nanoelectromechanical pressure
sensors using Si membranes and either Si or Au-coated Si substrates. It is
shown that if, under the influence of external pressure, the membrane-substrate
separation drops to below 100 nm, the Casimir force makes a profound effect on
the sensor functioning. There exists the maximum value of external pressure
depending on the sensor parameters such that it finds itself in a state of
unstable equilibrium. For this and larger pressures, the Casimir force leads
to a collapse of the sensor, which loses its functionality. For any smaller
external pressures, there exist two equilibrium positions, one of which is
unstable and another one is stable, at smaller and larger membrane-substrate
separations, respectively. The latter can be safely used for the pressure
measurements. Possible applications of the ontained results in the design of
micro and nano pressure sensors of next generations with further decreased
dimensions are discussed.
Jiang et al
In this work, we will consider the star network scenario where the central party is trusted while all the edge parties (with a number of $n$) are untrusted. Network steering is defined with an $n$ local hidden state model which can be viewed as a special kind of $n$ local hidden variable model. Two different types of sufficient criteria, nonlinear steering inequality and linear steering inequality will be constructed to verify the quantum steering in a star network. Based on the linear steering inequality, how to detect the network steering with a fixed measurement will be discussed.
Cui et al
Two-dimensional (2D) Bi2O2Se has been widely used as optoelectronic detectors due to its excellent carrier mobility and environmental stability. However, the synthesis of the p-type Bi2O2Se remains challenging which hinders its further applications. In this paper, we have investigated the electronic properties of the native point defects and the Ca/Cd-doping effects on Bi2O2Se using first-principles calculations. The results indicate that Se vacancy (VSe) and O vacancy (VO) are shallow donors, which lead to the n-type Bi2O2Se semiconductor. Ca substituting Bi (CaBi) and Cd substituting Bi (CdBi) are accepters and can compensate the n-type behavior of shallow donors. The compensation effect of CdBi is weaker than that of CaBi due to its higher formation energies. Additionally, the calculation results of the Fermi level, defect and carrier concentrations indicate that CaBi shifts the Fermi level towards the valence band maximum (VBM), however, it is not sufficient to convert Bi2O2Se into the p-type.
Pal et al
A solid-state experiment based on quantum tunneling is proposed
to reproduce the natural numbers and prime numbers as resonant
tunneling energies in a double barrier system (DBS). For getting
the prime numbers as eigenvalues the well potential is considered
as the superposition of a smooth potential which is estimated using
semi-classical approach and a weak local fluctuating potential. We
use the transfer matrix approach and finite element method by
taking only the smooth part of the potential to obtain resonant
energies which reproduces the local average prime density and the
local average prime gap exactly. The methodology when applied
to a quadratic potential of the well, produces whole numbers as
eigenvalues except for a constant zero-point energy-the energy
levels of a simple harmonic oscillator.
Lu et al
When individuals or companies are unable to meet their financial obligations, they may undergo the process of bankruptcy and go out of business. At the same time, new companies may arise. In this work, we propose a coevolutionary game model incorporated with bankruptcy. In the model, each agent represents a company. Two factors, accumulated payoff and age, are taken into account to determine its bankrupt probability. We assume two possible bankrupt mechanisms, procedural bankruptcy and age-dependent bankruptcy. Through numerical simulations, we show that the bankruptcy can effectively promote cooperation. Moreover, we find the non-monotonic behavior of the cooperation level with the increase of noise intensity in procedural bankruptcy. By investigating the strategy patterns and the distributions of the bankruptcy probabilities for cooperators and defectors, we provide explanations for the promotion of cooperation and the optimization of the cooperation level. This work highlights the positive effects of bankruptcy mechanism on cooperation in the real business world.
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Qi Gao et al 2024 EPL 146 31001
We analyze the static response to kinetic perturbations of nonequilibrium steady states that can be modeled as diffusions. We demonstrate that kinetic response is purely a nonequilibirum effect, measuring the degree to which the Fluctuation-Dissipation Theorem is violated out of equilibrium. For driven diffusions in a flat landscape, we further demonstrate that such response is constrained by the strength of the nonequilibrium driving via quantitative inequalities.
André Thiaville and Jacques Miltat 2024 EPL
The fine structure and dynamics of magnetic domain walls in ultrathin films with perpendicular magnetization, in presence of a secondary anisotropy, is analysed owing to micro-magnetics. Two cases are considered, a cubic anisotropy typical for (111) oriented garnet epitaxial films, and an orthorhombic anisotropy as found in e.g. Co/W(110) films. The statics is solved first, showing that, in general, domain walls are not of the pure Bloch type. The dynamics under the spin Hall effect induced by a current flowing in an adjacent layer is then monitored. Finite and non-negligible domain wall velocities are predicted in both cases, in the absence of Dzyaloshinskii-Moriya interactions, with distinct behaviours regarding the current density and its orientation with respect to the secondary anisotropy axes. The relevance of these results to recent reports of current driven domain wall dynamics in insulating ultrathin garnet films, capped with platinum, is discussed.
E. K. Luckins et al 2024 EPL 146 33001
We consider a liquid containing impurities saturating a porous material; when the liquid evaporates, the impurities are deposited within the material. Applications include filtration and waterproof textiles. We present a mathematical model incorporating coupling between evaporation, accumulation and transport of the impurities, and the impact of the deposited impurities on the transport of both the suspended impurities and the liquid vapour. By simulating our model numerically, we investigate the role of temperature and repeated drying cycles on the location of the deposited impurities. Higher temperatures increase the evaporation rate so that impurities are transported further into porous material before depositing than for lower temperatures. We quantify two distinct parameter regimes in which the material clogs: i) the dry-clogging (high-temperature) regime, in which impurities are pushed far into the material before clogging, and ii) the wet-clogging (high-impurity) regime, in which liquid becomes trapped by the clogging. Clogging restricts the extent to which drying time can be reduced by increasing the temperature.
Hoda Abdolalizadeh and Ekrem Aydiner 2024 EPL
In this study, using von Neumann entropy we examine the entanglement entropy for the neutrino oscillations in the presence of the subsequent phase shift. We numerically show that the entanglement entropy for the subsequent periods of the two-flavor neutrino oscillations increases asymmetrically with time depending on the space-time deformation. We also explored the obtained results for the three-flavor neutrino oscillations to show that this result is also valid for the three-flavor neutrino oscillations. These results, obtained for the first time in this study, are quite different from the computing for the standard neutrino oscillation theory. We concluded that these interesting results play an important role in the cosmology.
Riccardo Cominotti et al 2024 EPL
Ultracold atomic spin mixtures develop rich and intriguing magnetic properties when external radiation coherently couples different spin states. In particular, the coupled mixture may acquire a critical behavior when the spin interactions equal the coupling energy. 
However, atomic mixtures generally feature a relatively high sensitivity to magnetic fields that can set a limitation to the observable phenomena.
In this article, we present an overview of experimental studies of magnetism based on superfluid multicomponent gases in an ultrastable magnetic field environment, which recently became available.
Davide Venturelli et al 2024 EPL 146 27001
We develop a framework for the stochastic thermodynamics of a probe coupled to a fluctuating medium with spatio-temporal correlations, described by a scalar field. For a Brownian particle dragged by a harmonic trap through a fluctuating Gaussian field, we show that near criticality (where the field displays long-range spatial correlations) the spatially-resolved average heat flux develops a dipolar structure, where heat is absorbed in front and dissipated behind the dragged particle. Moreover, a perturbative calculation reveals that the dissipated power displays three distinct dynamical regimes depending on the drag velocity.
P. A. Varotsos et al 2024 EPL 146 22001
Upon employing the new concept of time, termed natural time, the analysis of seismicity reveals that, before major earthquakes, the variations of the Earth's electric and/or magnetic field are accompanied by increase of the fluctuations of the entropy change of seismicity under time reversal as well as by decrease of the fluctuations of the seismicity order parameter. Hence, natural time analysis reveals that before major earthquakes independent datasets of different geophysical observables (seismicity, Earth's magnetic and/or electric field) exhibit changes, which are observed simultaneously.
To the memory of the Academician Seiya Uyeda.
Jonas Skeivalas et al 2024 EPL
An ability to construct predictive models for identifying seismic oscillation parameters by using the mathematics of covariance functions and Doppler effect phenomena is examined in this work. In the calculations, the Mars seismic oscillations measurement data from InSight Mission V2, observed in the months 05, 06 and 07 of 2019, was used. To analyze the observation data arrays the Doppler phenomena and the expressions of covariance functions were employed. The seismic oscillations trend's intensity vectors were assessed by least squares method, and the random errors of measurements at the stations were eliminated partially as well. The estimates of the vector's auto-covariance and cross-covariance functions were derived by altering the quantization interval on the general time scale while varying the magnitude of the seismic oscillation vector on the same time scale. To detect the mean values of z – the main parameter of Doppler expression - we developed formula by involving the derivatives of cross-covariance functions of a single vector and algebraic sum of the relevant vectors.
Hisa-Aki Tanaka et al 2024 EPL
Synchronisability of limit cycle oscillators has been measured by the width of the synchronous frequency band, known as the Arnold tongue, concerning external forcing.
We clarify a fundamental limit on maximizing this synchronisability within a specified extra low power budget, which underlies an important and ubiquitous problem in nonlinear science related to an efficient synchronisation of weakly forced nonlinear oscillators.
In this letter, injection-locked Class-E oscillators are considered as a practical case study, and we systematically analyse their power consumption;
our observations demonstrate the independence of power consumption in the oscillator from power consumption in the injection circuit and verify the dependency of power consumption in the oscillator solely on its oscillation frequency.
These systematic observations, followed by the mathematical optimisation establish the existence of a fundamental limit on synchronisability, validated through systematic circuit simulations.
The results offer insights into the energetics of synchronisation for a specific class of injection-locked oscillators.
George Livadiotis and David McComas 2024 EPL
This paper reveals the universality of the particle energy distribution function, despite the arbitrariness that characterizes the generalized thermodynamic entropic function. We show that the canonical distribution, that is, the distribution function that maximizes this entropy under the constraints of canonical ensemble, is always the same and given by the kappa distribution function. We use the recently developed entropy defect to express the generalized entropic formulation. The entropy defect is a thermodynamic concept that describes the loss of entropy due to the order induced by the presence of correlations. Then we carry out functional analysis to maximize the implicit expression of the generalized entropy. Critically, we show that the Lagrange multipliers have the same exact arbitrariness as the generalized entropic function, allowing us to cancel it out and proving the universality of canonical distribution as the kappa distribution function.