It is demonstrated experimentally that the effective separation of bidispersed microspheres (dust particles) in the underdamped and strongly coupled regime is realized using a designed dusty plasma ratchet. Experimental findings reveal that these dust particles can undergo directional transport at varying speeds, even moving in opposite directions depending on the discharge conditions, enabling successful particle separation. Numerical simulations of the plasma environment surrounding the dust particles are performed using fluid simulations of the capacitively coupled discharge of Argon. The simulation results indicate that the bidispersed dust particles are suspended at different balance heights within the plasma sheath and experience distinct ratchet potentials that govern their directional transport, resulting in varied flow velocities. The discovery of height-dependent transport of dust particles here provides insights of transport fundamental of underdamped strongly coupled particles in dusty plasma ratchets.

This paper presents a lattice Boltzmann (LB) method based on nonmaterial enthalpy (NME) to simulate the solidification process of the liquid phase in the presence of noncondensable gas. The method employs a nonmaterial enthalpy distribution function format, which fundamentally avoids the issue of cross-distribution of thermal physical property parameters between different components that we previously addressed in our work [Dai et al., Phys. Rev. E 110, 025301 (2024)], using an enthalpy distribution function. Additionally, it overcomes the problem of low precision in latent heat treatment in the temperature distribution function's source term. Benefiting from the advantage that nonmaterial enthalpy distribution function (NMEDF) has the same dimension as temperature, the error associated with high-density gradients can be addressed by referring to the mature LB method already applied to boiling models [Li et al., Phys. Rev. E 105, 025308 (2022)]. Considering that the actual solidification process involves changes in density and volume, we introduced the modified linear state equation density-volume variation model, which enables simultaneous changes in both density and volume. Numerical results indicate that the LB method based on NME accurately captures the impact and subsequent solidification process of a water droplet on a cold surface in air, in agreement with experimental results, and effectively represents the significant differences in the thermal physical properties of air and water.

The speed of sound of simple dense fluids exhibits a pronounced freezing temperature scaling of the form $c_{\mathrm{s}}/v_{\mathrm{T}}\simeq \sqrt{\gamma }+\alpha {(T_{\mathrm{fr}}/T)}^{\beta }$, where $c_s$ is the speed of sound, $v_{\mathrm{T}}$ is the characteristic thermal velocity, $\gamma$ is the ideal gas heat capacity ratio, $T$ is the temperature, $T_{\mathrm{fr}}$ is the freezing temperature, and $\alpha$ and $\beta$ are dimensionless parameters. For the Lennard-Jones fluid, we get $\gamma =5/3$, $\alpha \simeq 7$ with a weak temperature dependence, and $\beta =1/3$. Similar scaling works in several real liquids, such as argon, krypton, xenon, nitrogen, and methane. In this case, $\alpha$ and $\beta$ are substance-dependent fitting parameters. A comparison between the prediction of this freezing temperature scaling and a recent experimental measurement of the speed of sound in methane under conditions of planetary interiors is presented and discussed. The results provide a simple, practical tool to estimate the speed of sound in regimes where no experimental data are yet available.

Active matter composed of self-propelled particles features fascinating self-organization phenomena, spanning from motility-induced phase separation to phototaxis to topological excitations depending on the nature and parameters of the system. In the present paper, we consider micelle formation by active particles with a broken symmetry having a circular back and a sharpened nose toward which the particles accelerate. As we demonstrate in experiments with robotic swarms, such particles can either remain in the isotropic phase or form micelles depending on the location of their center of inertia, in accordance with a recent theoretical proposal [T. Kruglov and A. Borisov, Presentations and Videos to 7th Edition of the International Conference on Particle-based Methods (2021), Vol. CT07, p. 2]. Such a behavior is observed for both nonchiral particles moving linearly and placed in a parabolic potential and for chiral particles moving along circular trajectories on a flat surface. By performing experiments with single robots and two-robot collisions, we unveil that the observed emergence of micellization associated with shifting robots' center of inertia towards their noses is governed by at least two-particle effects, in particular, by a difference in the formation of stable two-robot clusters. Finally, we consider the dependence of micelle lifetime and formation probability as well as two-robot collisions on friction between the lateral surfaces of the robots. Crucially, the predicted micellization does not involve any solvation shells that give rise to the micellization of surfactants but is instead driven by an interplay of activity and particle shape asymmetry.

The term Parrondo's paradox refers to the apparently paradoxical effect whereby two or more dynamics in which a given quantity decreases are combined in such a way that the same quantity increases in the resulting dynamics. We show that Parrondo's paradox can occur not only in the case of homogeneous but also in space-inhomogeneous one-dimensional discrete-time quantum walks. Moreover, we demonstrate that for such quantum walks Parrondo's paradox can affect the time evolution of quantum entanglement differently than it does in the case of homogeneous ones.

The model of localized fermions on the triangular lattice is analyzed in means of the Monte Carlo simulations in the grand canonical ensemble. The Hamiltonian of the system has a form of the extended Hubbard model (at the atomic limit) with nearest-neighbor Ising-like magnetic $J$ interactions and onsite Coulomb $U$ interactions. The model is investigated for both signs of $J$, arbitrary $U$ interaction, and arbitrary chemical potential $\mu$ (or, equivalently, arbitrary particle concentration $n$). Based on the specific heat capacity and sublattice magnetization analyses, the phase diagrams of the model are determined. For ferromagnetic case ($J<0$), the transition from the ordered phase (which is a standard ferromagnet and can be stable up to $k_{B}T/\left|J\right|\approx 0.61$) is found to be second order (for sufficiently large temperatures $k_{B}T/\left|J\right|\gtrsim 0.2$) or first order (for $-1<U/\left|J\right|<-0.65$ at the half-filling, i.e., $n=1$). In the case of $J>0$, the ordered phase occurs in a range of $-1/2<U/\left|J\right|<0$ (for $n=1$), while for larger $U$ the state with short-range order is also found (also for $n\ne 1$). The ordered phase is characterized by an antiferromagnetic arrangement of magnetic moments in two sublattices forming the hexagonal lattice. The transition from this ordered phase, which is found also for $\mu \ne 0$ ($n\ne 1$) and $U/\left|J\right|>-1/2$ is always second order for any model parameters. The ordered phase for $J>0$ can be stable up to $k_{B}T/\left|J\right|\approx 0.06$.

Using ordinal patterns for the time-series analysis of complex and chaotic dynamics in systems across a wide variety of physical, biological, and other phenomena has proven extremely powerful, with recent work exploiting metrics that also characterize symmetries and correlations underlying the complex dynamics. For that purpose we introduce here a geometrical representation for the ordinal pattern description of observed time series. We show that specific projections of this space, emphasizing time reversal symmetry, reveals information about the phase-space dynamics and identifies families of chaos and periodicity via the trajectories created as a function of parameter across this (approximate) dynamical-symmetry space. We discuss general consequences and specific applications of these observations.

This paper presents a simple model for such processes as chaos spreading or turbulence spillover into stable regions. In this simple model the essential transport occurs via inelastic resonant interactions of waves on a lattice. The process is shown to result universally in a subdiffusive spreading of the wave field. The dispersion of this spreading process is found to depend exclusively on the type of the interaction process (three- or four-wave), but not on a particular underlying instability. The asymptotic transport equations for field spreading are derived with the aid of a specific geometric construction in the form of a comb. The results can be summarized by stating that the asymptotic spreading proceeds as a continuous-time random walk (CTRW) and corresponds to a kinetic description in terms of fractional-derivative equations. The fractional indexes pertaining to these equations are obtained exactly using the comb model. A special case of the above theory is a situation in which two waves with oppositely directed wave vectors couple together to form a bound state with zero momentum. This situation is considered separately and associated with the self-organization of wave-like turbulence into banded flows or staircases. Overall, we find that turbulence spreading and staircasing could be described based on the same mathematical formalism, using the Hamiltonian of inelastic wave-wave interactions and a mapping procedure into the comb space. Theoretically, the comb approach is regarded as a substitute for a more common description based on quasilinear theory. Some implications of the present theory for the fusion plasma studies are discussed and a comparison with the available observational and numerical evidence is given.

Temperate phages, which can either kill their host cells or integrate into them, struggle to compete with purely virulent phages in environments with plenty of available hosts. This suggests that their survival strategy is fine tuned for unstable conditions, where they hedge their bets between immediate replication and long-term persistence as an integrated prophage. In this study, we explored how temperate phages make these life-or-death decisions, both in isolation and when competing with other phages. We found that when temperate phages compete with each other, those with relatively stable lysogens survive better. Environments with competitive temperate phages further select for lower lysogeny frequency. Our findings suggest that dosage-dependent lysogeny choice is adapted to competing phages with overlapping immunity. In environments where phages can disperse between separate subsystems that fluctuate independently, temperate phages struggle to survive against virulent phages.

We develop theoretical models for microscale breakdown under extremely high electric field conditions, by incorporating physical mechanisms associated with extremely strong electric fields, such as field emission, electron runaway, ion impact ionization, and the dynamics of fast atoms, which allows for accurate predictions of trends observed in existing experiments and simulations. Specifically, the mechanisms of breakdown characteristics exhibiting a multivalued curve in helium and a single-valued curve in argon are explicitly revealed. The results from the presented model also indicate that strong field-driven heavy particle reactions occur preferentially between smooth electrodes rather than rough electrodes in a microgap. Furthermore, simplified breakdown models tailored for argon and helium under strong field conditions are proposed after excluding less significant processes, providing theoretical references for the insulation design of miniaturized gaseous electronic devices.

We investigate static and dynamic behaviors of experimentally realized strongly coupled two-dimensional finite clusters in a complex (dusty) plasma. Clusters, ranging in size from $N$ (number of grains) = 1 to 50 are obtained using a highly precise control arm assembly BECAA (bidirectional electrode control arm assembly) [R. Kumar et al., Rev. Sci. Instrum. 95, 053503 (2024)], without any gaps and maintaining constant plasma discharge conditions. Crystalline (static) behavior of these clusters is characterized by the pair correlation function, shell structures,- and configurations, which are found to be in good agreement with simulation and previous experiments. The dynamic behavior of a cluster is quantified through recorded trajectories of individual grains and identification of their respective shells over time. Quantities such as angular rotation, intershell transitions and different regimes of mean-squared displacement (MSD) are highlighted to provide insights into the transition from individual to collective or bulk behavior of clusters. These transitions are typically studied via simulations due to significant challenges in controlling the number of grains in a complex plasma, whereas simulations allow easy adjustment of grain number. We have overcome this hurdle using BECAA and produced clusters with $N=1–50$ systematically and investigated their structures and dynamic properties to understand the individual-to-continuum transition.

The effects of an alternating electric field on the rose water model were studied. The rose water model is a simple two-dimensional water model consisting of Lennard-Jones disks to which an explicit hydrogen bonding potential has been added. To allow the model to interact with the electric field, partial charges were added to the original model. Changes in the structure, dynamics, and thermodynamics of the water due to fluctuations in the electric field were observed, as the effect of the field on the water depends on the frequency and strength of the electric field as well as on the initial properties of the water, such as the degree of hydrogen bonding. The electric field used is in the frequency and strength range corresponding to the rotational motion of the molecules, so the field affected the system by increasing the rotation of the water molecules. Depending on the frequency of the field, three ranges were observed in which the effects were different. In the low frequency range, the effects of the alternating field were similar to the effects of a constant static electric field, while at high frequencies the field has practically no effect on the water. The frequency range of interest is close to the natural frequency of rotation of the water molecule, where the resonance occurs. We have developed a model that explains both the rotational absorption spectra and the resonance frequency. The model establishes a link between the hydrogen bonding of water molecules and their resonance frequency in electric fields of different strengths.

Continuum models are commonly used to study dendritic deposition in fields ranging from nonequilibrium statistical mechanics to battery research. However, the continuum approximation underlying these models is poorly understood, even in the simplified case of Brownian particles depositing onto a small, reactive cluster. Specifically, this system transitions from a compact to a dendritic morphology at a critical radius that depends on the particle size. But in simulations of the continuum (small-particle) limit, the critical radius does not reproduce the scaling predicted by a purely continuum analysis. This discrepancy suggests that continuum models may not be able to capture the microscopic physics of dendrite formation, raising doubts about their experimental relevance. To clarify the continuum limit of dendritic deposition, here, we reexamine the critical radius scaling of the Brownian particle system using Brownian dynamics simulations. Compared to past studies, we probe larger system sizes, up to hundreds of millions of particles in some cases, and adopt an improved paradigm for the surface reaction. This paradigm allows us to converge our simulations and to work with well-defined physical parameters. Our results show that the critical radius scaling is, in fact, consistent with the continuum analysis, validating the continuum approach to modeling dendritic deposition. Nonetheless, the Brownian particle system converges to its continuum limit slowly. As a result, when applying continuum models to more complex deposition processes, the continuum approximation itself may be a significant source of error.

The behavior of viscosity, $\eta$, as a function of concentration in dense fluids remains an unsolved problem, as is the case with other transport coefficients. Boltzmann's theory and the Chapman-Enskog method predict the value of the viscosity at low concentrations, ${\eta }_0$. Here, the hypothesis $\eta =\varphi {\eta }_0$ is proposed, where $\varphi$ is a function of the thermodynamic state that represents the effects of interactions as concentration increases. We consider that ${\eta }_0$ is the viscosity in an ideal hypothetical system, where the condition of small interactions applies for the whole density range ($\varphi \to 1$ for low concentration). The method proposed to verify this hypothesis involves coupling the system with a solvent represented by a Langevin thermostat, characterized by a damping time $t_d$. Molecular dynamics simulations show that different values of noise intensity modify $\eta$ and ${\eta }_0$, but do not affect $\varphi$. This result supports the assumption that $\varphi$ is a state function, since the thermodynamic state remains unaltered by the presence of damping and noise. Simulations were conducted for particles that interact via a pseudohard sphere or a Lennard-Jones potential.

A prototypical model of symmetry-broken active matter—biased quorum-sensing active particles (bQSAPs)—is used to extend notions of dynamic critical phenomena to the paradigmatic setting of driven transport, where characteristic behaviors are nonstationary and involve persistent fluxes. To do so, we construct an effective field theory with a single order-parameter—a nonstationary analog of active model B—that reflects the fact that different properties of bQSAPs can only be interpreted in terms of passive thermodynamics in appropriately chosen inertial frames. This codifies the movement of phase boundaries due to nonequilibrium fluxes between coexisting bulk phases in terms of a difference in effective chemical potentials and therefore an unequal tangent construction on a bulk free energy density. The result is both an anomalous form of coarsening and, more generally, an exotic phase structure; binodals are permitted to cross spinodal lines so that criticality is no longer constrained to a single point. Instead, criticality, with exponents that are seemingly unchanged from symmetric QSAPs, is shown to exist along a line that marks the entry to an otherwise forbidden region of phase space. The interior of this region is not critical in the conventional sense but retains certain features of criticality, which we term pseudocritical. While an inability to satisfy a Ginzburg criterion implies that fluctuations remain relevant at macroscopic scales, finite-wave-number fluctuations grow at finite rates and exhibit nontrivial dispersion relations. The interplay between the growth of fluctuations and the speed at which they move relative to the bulk results in distinct regimes of micro- and meso-phase separation.

We simulate the $N$-spin critical Ising model on a square lattice using Glauber dynamics and consider the typical one-unit time equal to $N$ single-spin-flip attempts. The divergence of correlation time with the linear extent of the system results in critical slowing down, a challenge to equilibration because the spin configurations generated in such a way are temporally correlated. We examine temporal correlations in the number of accepted spin flips and show a signature of nontrivial long-time correlation of a logarithmically decaying form, or the corresponding power spectral density follows canonical $1/f$ noise.

We study the relaxation dynamics of a run and tumble particle (RTP) in a one-dimensional piecewise linear potential $U\left(x\right)=b\left|x\right|$, from delta-function initial conditions at $x=0$ to steady state. In addition to experiencing active telegraphic noise, the particle is in contact with a heat bath at temperature $T$ that applies white thermal noise. We find that the position distribution of the RTP is described by a sum of two distributions (“modes”), each of which of the form $P(x,t\to \infty )\sim e^{-{\lambda }_i\left|x\right|}$ ($i=1,2$) at steady state. The two modes are dynamically coupled: At very short times ($t\to 0$), each mode stores half of the probability, and exhibits thermal diffusive spreading with a Gaussian profile. With progressing time and evolution toward steady state, the partition of probability between the modes becomes increasingly uneven, and, depending on the model parameters, the mode with the smaller value of ${\lambda }_i$ may carry an overwhelming majority of the probability. Moreover, we identify that the characteristic relaxation time of each mode is ${\tau }_i={\left({\lambda }_i^{2}T\right)}^{-1}$, which implies that the minority mode also relaxes much faster than the dominant one. A more detailed analysis reveals that ${\tau }_i$ is characteristic of the mode relaxation only close to the origin at the core of the distribution, while farther away it increases linearly with $\left|x\right|$ as if a relaxation front is propagating at constant speed $v_i^{*}=2\sqrt{T/{\tau }_i}$ in the system. The rate of nonequilibrium entropy production can be related to the two-mode splitting of the probability distribution and be expressed in terms of their correlation lengths ${\lambda }_i$ and their contributions to the steady-state distribution.

The chaotic phase of the tilted Bose-Hubbard model is identified as a function of energy, tilt strength, and particle interaction, from the eigenstate structure and the statistical features of the energy spectrum. Our analysis reveals that the chaotic phase of the bare Bose-Hubbard Hamiltonian can be enhanced by the presence of a moderate tilt. We further unveil the development and scaling of the chaotic regime from the perspective of a homogeneous density configuration typically used in cold atom experiments, providing a valuable phase diagram for future theoretical and experimental studies of this system.

We investigate the dynamics of nondegenerate Akhmediev breathers (ABs) in both the time and frequency domains within a three-wave resonant interaction system. In contrast to the conventional degenerate ABs, the nondegenerate ABs are composed of two fundamental ABs, each having an individual gain spectrum and exhibiting distinct structural configurations. We first presented the existence regions of degenerate and nondegenerate ABs, and then we numerically simulated the instability process of weak periodic perturbations on a plane wave and verified the results by integrating them with the exact AB solutions. Additionally, we provided a detailed explanation of the observed phenomena based on the instability analysis of the TWRI system.

We calculate the eigenvalues of a class of random matrices, namely, the randomly segmented tridiagonal quasi-Toeplitz matrix (rstq-T), in exact closed form. The contexts under which these matrices arise are ubiquitous in physics. In our case, they arise when studying the dynamics of a Rouse polymer embedded in random environments. Unlike in the case of Rouse polymers in homogeneous environments, where the dynamics gives rise to a circulant matrix and the diagonalization is easily achieved via a Fourier transform, analytical diagonalization of the rstq-T matrix has remained unsolved thus far. We analytically calculate the spectral distribution of the rstq-T matrix, which is able to capture the effect of disorder on the modes.