arXiv subjects

Lam Thi Nhung

Publications and source records attributed to Lam Thi Nhung.

3 recordsLinked to original sources

arXiv2026

Invariant measures of exclusion processes with a look-ahead rule

We study a one-dimensional exclusion process with a fixed jump length $I \ge 1$ in which a particle may advance or retreat $I$ sites provided all intermediate sites are vacant, with hopping rates of Arrhenius type depending on the local headway. We identify the class of rates admitting an explicit Ising-Gibbs invariant measure, with stationarity governed by pairwise balance rather than detailed balance. In the thermodynamic limit, we derive a closed-form stationary current that recovers the mean-field prediction for look-ahead traffic-flow models exactly when particles are uncorrelated, and quantifies the correlation-induced correction otherwise. The resulting fundamental diagram is right-skewed and non-concave, as in empirical traffic data, and for a preferred-spacing interaction-where the stationary headway distribution becomes bimodal-the mean-field approximation fails qualitatively. The closed-form current is confirmed by kinetic Monte Carlo simulations and by exact finite-size computations.

cond-mat.stat-mech↗

arXiv2026

Tandem Exclusion Process

We introduce the \emph{tandem exclusion process} (TEP), a one-dimensional stochastic lattice model motivated by tandem running in ants. Particles evolve through two cooperative local transitions, $110\to101$ at rate $α$ (leader advancement) and $101\to011$ at rate $β$ (follower recovery). We prove that the stationary measure on the dynamically active sector is the Gibbs measure $π\propto q^{H(η)}$, where $q=β/α$ and $H(η)$ counts neighboring occupied pairs, and derive exact closed-form expressions for the stationary current and spatial correlations using transfer-matrix methods. The current is asymmetric under particle--hole exchange $ρ\mapsto1-ρ$, with its maximum occurring at densities strictly larger than $1/2$, in contrast to the symmetric current $ρ(1-ρ)$ of the totally asymmetric simple exclusion process (TASEP). For $q>1$, cooperative dynamics enhances the current above the TASEP value and generates strong spatial clustering; in the limit $q\to\infty$, the current approaches $J\toαρ$, corresponding to nearly unconstrained collective transport. These results suggest that tandem coordination alone can substantially enhance collective transport efficiency at moderate and high densities, even without pheromone-mediated long-range communication.

cond-mat.stat-mech↗

arXiv2025

A Class of Exclusion Processes Capable of Exhibiting Current Reversal

A century after Ising introduced the Ising measure to study equilibrium systems, its relevance has expanded well beyond equilibrium contexts, notably appearing in non-equilibrium frameworks such as the Katz--Lebowitz--Spohn (KLS) model. In this work, we investigate a class of generalized asymmetric simple exclusion processes (ASEP) for which the Ising measure serves as the stationary state. We show that the average stationary current in these models can display current reversal and other unconventional behaviors, offering new insights into transport phenomena in non-equilibrium systems. Moreover, although long-range interaction rates often give rise to long-range interactions in the potential function, our model provides a counterexample: even with long-range interactions in the dynamics, the resulting potential remains short-ranged. Finally, our framework encompasses several well-known models as special cases, including ASEP, the KLS model, the facilitated exclusion process, the cooperative exclusion process, and the assisted exchange model.

cond-mat.stat-mech↗