We numerically study the flow of dense granular materials between parallel plates driven by an external force. The granular materials form a jammed solidlike state when the external force is below a critical force, while they flow like fluids above the critical force. The transition is characterized by the mass flux. The critical force depends on the average packing fraction and the distance between the plates. The scaling laws for the critical force and the mass flux are theoretically predicted based on a continuum model, and are numerically verified.

The directed motion of active colloids is governed by spatial variations in surface chemistry that generate effective interfacial flows, yet the resulting slip distributions remain extremely difficult to measure directly. We introduce a physics-informed neural network framework that infers the slip distribution driving propulsion from partial observations of the surrounding flow. By combining partial fluid-velocity measurements with the Stokes equations and boundary constraints, the method reconstructs both the near-surface slip and the full velocity field. Validation against analytical solutions and boundary element method calculations for canonical active colloid models shows quantitative agreement in both unbounded and confined geometries. Systematic tests identify the conditions under which the reconstruction degrades as measurement availability decreases or noise increases, while comparison with radial-basis-function interpolation demonstrates the importance of the governing equations for recovering the data-free near-surface flow. Crucially, the framework recovers the surface slip even when no flow data are available near the particle, demonstrating that accessible bulk measurements encode the effective surface slip associated with active motion.

We solve exactly the transient two-dimensional advection diffusion problem generated by one and two semi-infinite internal Dirichlet lines, representing slender dendrites advancing into a supersaturated liquid while fixing the solute concentration on their surfaces. For a single dendrite, the mixed boundary value problem is reduced to a Wiener-Hopf equation, factorized explicitly, and inverted to the time domain by the Cagniard-de Hoop method, yielding the single-layer density in closed form in terms of the complex error function. For two parallel dendrites separated by a lateral distance $h$, the interaction enters through the transcendental kernel ${(1+e^{-\kappa h})}^{-1}$, whose lower Wiener-Hopf factor is represented by a logarithmic Cauchy integral, and the resulting finite distance feeding field is reduced to a regularized oscillatory integral. The exact two-dendrite solution reveals a structural obstruction to purely local growth laws: the leading inverse square-root tip singularity is universal, with identical amplitudes for both dendrites independently of spacing, even though the neighbor modifies the feeding field at every finite distance behind the tip. Competition therefore cannot be encoded in any local tip amplitude alone. This obstruction forces a nonlocal coupling variable, which we identify as a finite tip zone functional that retains the subleading near tip structure responsible for competitive depletion. The interaction further resolves into a discrete hierarchy of exponentially screened modes with dominant screening length $h/\pi$, which sets the natural scale of competitive suppression. These exact transport results provide the analytical backbone for a reduced theory of dendrite arrest and winner selection, and are validated against independent finite-difference computations.

A solidifying dendrite advancing toward an oblique impermeable wall senses the wall through reflection of its own diffusive depletion field. The strength of this reflection depends on both wall obliquity and the unsteady kinematics of the closing gap, and cannot be captured by any quasistatic frozen offset construction. We solve the moving boundary diffusion problem exactly in the laboratory frame (wall fixed, dendrite advancing at constant speed) by recasting it as a Wiener-Hopf-Hankel system on a pair of spectral branches. The resulting upper triangular operator is inverted sequentially: first as a Fredholm integral equation on the lower branch, then as a scalar Wiener-Hopf problem on the upper branch, reaching a closed form solution via Cagniard-de Hoop. A Padé-Abrahams rational reduction of the spectral radical reduces the entire scheme to a low cost algebraic system at each Laplace node. The exact unsteady solution inverts the classical starvation picture. Measured against an isolated dendrite at the same elapsed time, the wall correction is weakly suppressive while the tip is more than about two diffusion lengths from the wall, where the reflected depletion returns with little retardation and acts as ordinary blockage, but the suppression never exceeds one percent. As the gap closes the correction changes sign and the feeding rises to 31 percent above the isolated reference at grazing incidence, because the reflected field carries a memory of wider past gaps and delivers more solute than the instantaneous geometry would allow. The enhancement is governed by the oblique Péclet number ${\text{Pe}}_{\theta }=v{d}_{0}sin\theta /D$ and is strongest at grazing incidence, where it exceeds the preceding suppression by a factor of 30.

We show that stochastically driven nonequilibrium conserved growth models admit generic strong coupling phases for sufficiently strong nonlocal chemical potentials underlying the dynamics. The models exhibit generic roughening transitions between perturbatively accessible weak coupling phases satisfying an exact relation between the scaling exponents in all dimensions $d$, and strong coupling phases. In dimensions at or below the critical dimension $d_c$, the latter phases are unstable and argued to be crumpled, and thus distinct from the well-known strong coupling rough phase of the Kardar-Parisi-Zhang equation in dimensions $d\ge 2$. At $d_c$, conventional spatiotemporal scaling in the weak coupling phase is logarithmically modulated and are exactly obtained.

Measuring transport coefficients at the microscale remains challenging, often relying on indirect methods that require modeling and calibration. This article derives universal asymptotic forms for the autocorrelation and relative uncertainty of local probe measurements in dilute diffusive systems. Valid both at and far from equilibrium, these forms directly connect microscopic measurements to the effective diffusivity. Indirect methods such as dynamic light scattering and fluorescence correlation spectroscopy can therefore serve as asymptotically direct probes applicable to active and other microscopically nondiffusive systems. Simulations across several models and observables confirm the broad applicability of these predictions to a variety of probes.

Estimating entropy production in continuous systems that can only be observed with a limited resolution remains an open problem in stochastic thermodynamics. Existing estimators based on the measurement of waiting-time distributions either require the detection of Markovian events, which uniquely determine the state of the system, or assume a discrete underlying dynamics. We present a novel estimator that relies solely on the detection of a single particle leaving or entering regions, or crossing manifolds, in continuous space. This estimator is based on the frequency and the duration of transitions between such events. We derive this bound by introducing two kinds of discretization of space. Finally, we compare our novel bound to the thermodynamic uncertainty relation improved by correlations using simulations of a Brownian vortex, and we discuss its relation to other lower bounds to entropy production.

We conduct numerical simulations of a noisy generalized Kuramoto-Sivashinsky system under optimal control. The cost functions are kinetic energy and permutation entropy, which are designed to reduce the kinetic energy and the permutation entropy, respectively. The results demonstrate that kinetic-energy-based control strongly suppresses the structures and drives the system into a trivial state. In contrast, the permutation-entropy-based control preserves nontrivial structures, although the reduction in kinetic energy is smaller and requires only slight actuation energy. These findings provide insight into designing control strategies for complex systems where both efficiency and functional richness are desired.

We investigate dust-acoustic rogue waves in a one-dimensional binary dusty plasma using analytical nonlinear Schrödinger equation theory and fully kinetic particle-in-cell simulations. Modulational instability initially drives nonlinear focusing and rogue-wave formation, consistent with fluid predictions. However, after the rogue-wave peak, the coherent structure collapses irreversibly due to kinetic effects instead of exhibiting periodic recurrence. The breakdown is caused by asymmetric kinetic heating between the two dust species. The lighter dust grains, owing to their lower inertia, absorb most of the wave energy through strong wave-particle interactions and develop non-Maxwellian energetic tails, while the heavy dust experiences only weak heating. In addition, the rogue-wave excitation time is highly sensitive to small changes in the imposed perturbation amplitude. These results demonstrate the kinetic and irreversible nature of rogue waves in realistic binary dusty plasmas.

Laser wakefield acceleration (LWFA) provides a compact platform for generating bright, ultrashort, and tunable x-ray betatron radiation. When the betatron oscillation wavelength matches the laser centroid oscillation period in a preformed plasma channel, resonance occurs, leading to a rapid amplification of the electron betatron oscillation amplitude and significantly increasing the photon energy and yield of the sources. However, nonideal conditions from laser-plasma interactions may drive electrons out of resonance rapidly. In this work we use particle-in-cell simulations and theoretical analysis to identify four distinct mechanisms that disrupt the resonant growth: the nonlinear focusing force at large radii, the dephasing between the wakefield and the electron beam, the acceleration or deceleration of the electrons, and the decay of the laser centroid oscillation amplitude caused by phase mixing among different laser slices. Detailed particle tracking reveals that a delicate balance between dephasing and acceleration can sustain electrons in resonance for an extended period. Building upon these physical insights, we optimize laser, electron beam, and plasma channels to significantly enhance the emitted radiation. These results provide valuable guidance for developing high-yield and high-energy betatron radiation sources based on LWFA.

We theoretically and experimentally investigate wave scattering in a single-column woodpile structure with impurities. This structure consists of slender cylindrical beams that support flexural bending modes, which are coupled strongly with propagating waves in the low-frequency regime (i.e., local resonance coupling). We examine the linear scattering of plane waves from single and double impurities in periodic configurations. When local resonance coupling is neglected, the double-impurity configuration exhibits reflectionless transmission, resembling the Ramsauer-Townsend (RT) resonance. Further analysis reveals that, under strong local resonance coupling, this behavior evolves into a Fano resonance, which features an asymmetric line shape with a sharp transition between transmission and reflection. However, as the RT resonance and the local resonance become spectrally closer, an analog of electromagnetically induced transparency (EIT) emerges, resulting from the balanced interference between the two modes. These distinct resonant behaviors can be tuned by varying the local resonance coupling strength, providing a controllable platform for macroscopic analogs of quantum wave interference. Potential applications include vibration isolation and wave-based switching devices.

The pore-surface and surface-surface correlation functions are structural characteristics that play an important role in theoretical materials science and in small-angle scattering theory. Symbolic expressions for the surface correlation functions are available only for very few models, and we here derive such expressions for the general class of dead-leaves models. Within these models, a two-phase pore-solid structure is created by sequentially and randomly filling space with porelike or solidlike grains that overlap any preexisting structure, in the same way that dead leaves fall on the ground. The obtained mathematical expressions are valid for any grain shape, in arbitrary dimension. The results are illustrated with monodispersed spherical grains as well as with a dead-leaves realization of a Debye random medium. In the latter case, the size distribution of the grains is designed to produce a structure having an exponential two-point correlation function. Compared to Debye random media obtained by numerical reconstruction, the dead-leaves structure has an almost identical surface-surface correlation function, but a distinctly different pore-surface correlation function with different average mean curvature of the pore-solid surface. Using the concepts introduced in the paper, we submit a general analytic expression for the pore-surface and surface-surface correlation functions of the Boolean model of interpenetrating grains, valid for arbitrary grains. We also derive general expressions for the surface correlation functions of mosaic structures.

One-dimensional alternating particle systems are widely used to study interconnections between the hydrodynamics of blast waves in a gas-like medium and the Newtonian dynamics of its corpuscular constituents. In this article, we study the model in which point particles with masses $m,\mu ,m,\mu ,\cdots , (m\ge \mu )$ are distributed on the positive half-line ${\mathbb{R}}_{+}$. Their dynamics are initiated by giving a positive velocity to the leftmost particle; in its course, the particles undergo elastic collisions. For this model with $m/\mu =2$, it has been established that the dynamics that start from random initial positions are consistent with predictions based on Euler's hydrodynamic equation. In particular, they have the following properties: (i) the position of the rightmost particle (shock front) evolves as $t^{\delta }$ with $\delta <1$; (ii) recoiled particles behind the front enter the negative half-axis; and (iii) particles with locations $x\le 0$ move ballistically and eventually take over the total energy of the system. In this paper, we present numerical and analytical results for the dynamics of this model with nonrandom (typically equidistant) initial positions and various values of $m/\mu$. For $m/\mu =2$ and equidistant initial positions, our results qualitatively agree with those just mentioned. At the same time, we found an infinite family of numbers $\left\{{\mathcal{M}}_k\right\}$ such that, for $m/\mu ={\mathcal{M}}_k$, the hydrodynamic behavior mentioned changes drastically to the following. At each moment, only a single triplet $m,\mu ,m$ is in motion, whereas all other particles are at rest. In the moving triplet, two heavy particles move to the right, while the lighter particle oscillates between them, transferring energy and momentum to the right. As a result, the shock front moves ballistically with an average velocity equal to the initial one. Such a ‘staggering domino-like’ picture is obtained as an exact solution, which yields, in particular, explicit formulas for ${\mathcal{M}}_k$ and the particle velocities and positions. Its details and importance in a wider context are also discussed.

We extend the canonical Gibbs distribution, originally formulated for systems at equilibrium, to systems driven out of equilibrium. The stochastic dynamics of a small system are described by a probability distribution over discrete energy levels. Within this framework, we derive a microscopic expression for work and introduce a microscopic definition of entropy production (defined here in terms of the uncompensated heat of Clausius) during a nonequilibrium stochastic process. Work and entropy production share a common origin arising from variations of the system energy. The proposed framework allows us to recover the nonequilibrium work relation and to establish an equivalent identity for the heat exchanged during a work protocol. Finally, we show that the fluctuations of work and heat governed by the extended canonical distribution follow directly from the fluctuation theorem for entropy production.

It is an important physical property for a diffusion process to respond to an external force or a spatial confinement in experiments. This paper investigates the random diffusivity processes coupled with an inverse $\alpha$-stable subordinator which characterizes the trapping events in crowded environment, and studies its dynamics under the harmonic potential by evaluating the ensemble-averaged and time-averaged mean-squared displacements (MSDs). We build three kinds of coupled Langevin equations based on different physical realities of the external force in crowded environment, e.g., the harmonic potential only modifies the particle's motion at the moments of particle-making jumps, and that exerts an effect throughout the whole physical time, and the case with the validity of fluctuation-dissipation theorem. By comparing these three models, we find that the crowding trapping effect and temporal dynamic fluctuation play different roles in the MSDs. Nevertheless, we also observe an interesting phenomenon that the ratio between two MSDs exhibits the same scaling form, which perhaps reveals an underlying mechanism of the ergodicity breaking within the subordinated diffusion processes.

Entanglement entropy is a fundamental diagnostic for quantum chaos, typically exhibiting volume-law scaling in highly excited eigenstates of chaotic many-body systems. In this work, we present a striking counterexample: a Floquet-driven quantum many-body system with a Rydberg-like blockade that, despite being fully chaotic as indicated by its Wigner-Dyson level statistics and local thermalization, exhibits a strict area-law entanglement entropy. Specifically, the entanglement entropy of every Floquet eigenstate is bounded by $ln2$, independent of system size. We trace this anomaly to the specific Hilbert space structure imposed by the blockades, which restricts the Schmidt rank across a bipartition. Furthermore, we generalize this discovery by establishing a duality between constrained many-body Hamiltonians and single-particle quantum walks on median graphs, and we outline a general procedure for constructing systems with an entanglement entropy bounded by a predetermined constant. Our results demonstrate that entanglement entropy alone is an insufficient diagnostic of many-body quantum chaos and highlight the profound impact of Hilbert space geometry on quantum dynamics and thermalization.

We study the kinetics of two-temperature induced phase separation in dilute binary mixtures of active (“hot”) and passive (“cold”) particles using molecular dynamics simulations and a coarse-grained hydrodynamic model. Following a temperature quench, cold particles nucleate into mobile clusters that move ballistically and merge through successive coalescence events. The resulting domain growth exhibits dynamic scaling with a growth exponent $\approx 0.7$, markedly faster than diffusive coarsening. We identify this regime as ballistic agglomeration of cold clusters, demonstrating a distinct nonequilibrium growth mechanism in low-density scalar active systems.

We experimentally investigate the dynamics of a spherical intruder driven horizontally at a constant force in a granular medium subjected to a localized surface overload. While intruder motion beneath a free surface exhibits constant acceleration in the quasistatic regime, the presence of a surface load induces a pronounced transient deceleration when the intruder passes below the loaded region. The magnitude of this deceleration increases with the applied overload and saturates at large overloads, while it decreases with intruder depth. Introducing a characteristic timescale and an overload-based Froude number, we show that the deceleration dynamics collapse onto master curves. We further develop a model incorporating stress transmission from the surface, which partially captures the intruder deceleration. In this approach, this deceleration is shown to depend on two parameters: the overload and the area on which this overload is applied. These results provide a framework to quantify how localized surface stresses influence subsurface intruder dynamics, with implications for locomotion, root growth, and underground transport in granular media.

A state-based ergodic approach is introduced using a descriptor constructed from instantaneous, spatially resolved measurements to quantify the spatiotemporal evolution of system states in far-from-equilibrium systems. This method is demonstrated for the mixing process in confined water-glycerol flows driven across three milli-scale geometries, by combining experiments with lattice Boltzmann simulations that uniquely incorporate colloids as passive flow obstacles. This generalizable framework distinguishes nonequilibrium pathways by tracking information about accessed system states.

We study the dynamic critical behavior of the two-dimensional random-bond three-state Potts model using large-scale Monte Carlo simulations with the Wolff and Swendsen-Wang cluster algorithms. At the disorder-dependent critical temperature, we compute integrated and exponential autocorrelation times and extract the dynamic critical exponent $z$ via finite-size scaling. Critical slowing down is significantly weakened by bond randomness, with the dynamic exponent decreasing from $z\approx 0.54$ in the pure system to $z\approx 0.24$ at strong disorder. From the finite-size scaling of the Wolff cluster size, we obtain $\gamma /\nu \approx 1.73$, where $\gamma$ and $\nu$ are the susceptibility and correlation-length exponents, respectively, consistent with the universality class of the two-dimensional three-state Potts model. These results indicate that bond randomness strongly affects the critical dynamics but leaves the underlying static universality class unchanged. Furthermore, both static and dynamic observables, including the specific heat and the autocorrelation times, show a lack of self-averaging.