Physical review. E最新文献

We consider the fractional Langevin equation far from equilibrium (FLEFE) to describe stochastic dynamics which do not obey the fluctuation-dissipation theorem, unlike the conventional fractional Langevin equation (FLE). The solution of this equation is Riemann-Liouville fractional Brownian motion (RL-FBM), also known in the literature as FBM II. Spurious nonergodicity, stationarity, and aging properties of the solution are explored for all admissible values α>1/2 of the order α of the time-fractional Caputo derivative in the FLEFE. The increments of the process are asymptotically stationary. However when 1/2<α<3/2, the time-averaged mean-squared displacement (TAMSD) does not converge to the mean-squared displacement (MSD). Instead, it converges to the mean-squared increment (MSI) or structure function, leading to the phenomenon of spurious nonergodicity. When α≥3/2, the increments of FLEFE motion are nonergodic, however the higher order increments are asymptotically ergodic. We also discuss the aging effect in the FLEFE by investigating the influence of an aging time t_{a} on the MSD, TAMSD and autocovariance function of the increments. We find that under strong aging conditions the process becomes ergodic, and the increments become stationary in the domain 1/2<α<3/2.

In this manuscript, we investigate the stochastic thermodynamics of Fisher information (FI), meaning we characterize both the fluctuations of FI, introducing a statistics of that quantity, and thermodynamic quantities. We introduce two initial conditions: an equilibrium initial condition and a minimum entropy initial condition, both under a protocol that drives the system to equilibrium. Its results indicate a dependence of the average FI on both the initial condition and path taken. Furthermore, the results indicate that the chosen parameter directly affects the FI of thermodynamic quantities, such as irreversible work and entropy, along with fluctuations of a stochastic FI. Last, we assess the further role of FI of the distribution of thermal quantities within the context of thermostatistical inequalities.

We explore chimera states in a ring of nonlocally coupled type-I excitable phase oscillators, with each isolated oscillator being restricted to a homogeneous equilibrium state. Our study identifies the presence of breathing chimera states, characterized by their oscillatory dynamics and periodic fluctuations in the global order parameter. Beyond the breathing chimera states with a single coherent cluster, we find the 2n-cluster breathing chimera states, where 2n represents an even number of coherent clusters. These states exhibit the varying phase difference between adjacent clusters and a consistent phase among clusters separated by one intermediate cluster. The number of clusters is found to be modulated by the relative coupling radius. These dynamics for the finite number of oscillators are well confirmed by the Ott-Antonsen ansatz.

Soft films serve as the primary support materials for flexible devices. These films are frequently peeled perpendicularly during device preparation and application, resulting in large compression on the upper surface of the bending region and significant damage to the device's performance. Accurately assessing this damage is challenging because of the difficulties in calculating the compression in perpendicularly peeled large-deformation films. In this study, we propose a method to calculate the compressive strain on the upper surface of a bending soft film using only its thickness as the key parameter. Furthermore, we demonstrate that the length of the compressive region is directly proportional to the soft film thickness, whereas the maximum strain is inversely proportional to the thickness. These results provide theoretical guidance for applying soft films in flexible devices.

In this article, we perform a systematic study of the global entanglement and exciton coherence length dynamics in natural light-harvesting system Fenna-Matthews-Olson (FMO) complex across various parameters of a dissipative environment from low to high temperatures, weak to strong system-environment coupling, and non-Markovian environments. A nonperturbative numerically exact hierarchical equations of motions method is employed to obtain the dynamics of the system. We found that entanglement is driven primarily by the strength of interaction between the system and environment, and it is modulated by the interplay between temperature and non-Markovianity. In contrast, coherence length is found to be insensitive to non-Markovianity. In agreement with previous studies, we do not observe a direct correlation between global entanglement and the efficiency of the excitation energy transfer in the FMO complex. As a new result, we found that the coherence length dynamics is correlated with the excitation energy transfer dynamics.

Several interesting and important natural processes are the manifestation of the interplay of nonlinearity and fluctuations. Stochastic resonance is one such mechanism and is crucial to explain many physical, chemical, and biological processes, as well as having huge technological importance. The general setup to describe stochastic resonance considers two states. Recently, it has been unveiled that it is necessary to consider the intrinsic fluctuations related to the two different states of the system are different in interpreting certain fundamental natural processes, such as glacial-interglacial transitions in Earth's ice age. This also has significance in developing advantageous technologies. However, until now, there has been no general theory describing stochastic resonance in terms of the transition rate between the two states and their probability distribution function while considering different noise amplitudes or fluctuation characteristics of these two states. The development of this fundamental theory is attempted in the present research work. As a first step, a relevant approximation is used in which the system is considered within the adiabatic limit. The analytical derivations are corroborated by numerical simulation results. Furthermore, a semianalytical theory is proposed for the definite system without any approximations as the exact analytical solution is not achievable. This semianalytical theory is found to replicate the results obtained from the Brownian dynamics simulation study for previously known quantifiers for stochastic resonance which are estimated in the present context for the system with state-dependent diffusion.

We examine anew the relationship of directed polymers in random media on traditional hypercubic versus hierarchical lattices, with the goal of understanding the dimensionality dependence of the essential scaling index β at the heart of the Kardar-Parisi-Zhang universality class. A seemingly accurate, but entirely empirical, ansatz due to Perlsman and Schwartz, proposed many years ago, can be put in proper context by anchoring the connection between these distinct lattice types at vanishing dimensionality. We graft together complementary perturbative field-theoretic and nonperturbative real-space renormalization group tools to establish the necessary connection, thereby elucidating the central mystery underlying the ansatz's uncanny apparent success, but also revealing its intrinsic limitations. Furthermore, we perform an extensive Euler integration of the KPZ equation in 3+1 dimensions which, bolstered by a separate directed polymer simulation, allows us an estimate for the critical exponent β_{3+1}^{KPZ}=0.1845(4) that greatly improves upon all previous Monte Carlo calculations in this regard and rules out the Perlsman-Schwartz value, 0.1882^{+}, in that dimension. Finally, leveraging this hybrid RG partnership permits us a versatile, more potent, tool to explore the general KPZ problem across dimensions, as well as a conjecture for its key critical exponent, β=1/2-0.22967ɛ, as ɛ→0, testable in a three-loop calculation.

We discuss a one-dimensional coupled qubit-array quantum battery model under Born-Karman boundary conditions and investigate both the charging and discharging processes. Applying the stored energy, charging power, and ergotropy as the essential physical indicators of quantum battery, it is observed that minimizing the hopping interaction between the nearest-neighbor qubits in the qubit-array and increasing the number of qubits during battery setup are crucial. Additionally, we employ a classical driving field to optimize battery performance and explore the optimal quantum battery performance by adjusting the driving strength of the classical field. Finally, we have discovered that the initial energy in the charger no longer needs to be higher than the energy in the battery in our protocol, the charger will continue to supply energy to the battery even when there is limited initial available energy in the charger. And the conventional approach of preparing the battery's initial state in its ground state, as observed in previous studies, may not necessarily be the optimal choice. By introducing a strong classical driving field, it is possible to enhance energy storage by allowing for an initial presence of some energy within the battery.

An analytical form has been derived using Ostrogradsky's integration method for the interaction between two thin rods of finite lengths in arbitrary relative configurations in a three-dimensional space, each treated as a line of point particles interacting through the Lennard-Jones 12-6 potential. Simplified analytical forms for coplanar, parallel, and collinear rods are also derived. Exact expressions for the force and torque between the rods are obtained. Similar results for a point particle interacting with a thin rod are provided. These interaction potentials can be widely used for analytical descriptions and computational modeling of systems involving rodlike objects such as liquid crystals, colloids, polymers, elongated viruses and bacteria, and filamentous materials including carbon nanotubes, nanowires, biological filaments, and their bundles.

Steady-state currents generically occur both in systems with continuous translation invariance and in nonequilibrium settings with particle drift. In either case, thermal fluctuations advected by the current act as a source of noise for slower hydrodynamic modes. This noise is unconventional, since it is highly correlated along spacetime rays. We argue that, in quasi-one-dimensional geometries, the correlated noise from ballistic modes generically gives rise to anomalous full counting statistics (FCS) for diffusively spreading charges. We present numerical evidence for anomalous FCS in two settings: (1) a two-component continuum fluid and (2) the totally asymmetric exclusion process initialized in a nonequilibrium state.