Casimir-like forces in cooperative exclusion processes

Abstract

I show that cooperative exclusion processes with selective kinetic constraints exhibit fluctuationinduced forces that can be attractive or repulsive, depending on the density of boundary reservoirs, when their density-dependent diffusion coefficient exhibits a minimum. A mean-field analysis based on a nonlinear diffusion equation provides an estimation of the magnitude and sign of such a tunable Casimir-like force and suggests its occurrence in interacting particle systems with a diffusivity anomaly.Casimir forces, experienced by objects immersed in a fluctuating medium with long-range correlations, are virtually present in all fields of physics, from exotic states of matter such as evaporating black holes, to the more ordinary liquid state structure (where they are embodied as van der Waals forces) and critical phenomena [1][2][3]. There has been a substantial theoretical and experimental effort to precisely characterize those physical situations where such forces are repulsive rather than attractive (see, for example, [4-10]), as initially found by Casimir in the ideal case of two parallel and perfectly conducting metal plates. This possibility, predicted by the Lifshitz theory when the dielectric properties of the plates and the intervening medium are properly chosen, offers the opportunity of engineering Casimir forces for the practical design of micro-and nano-structured electro-mechanical devices and materials [11,12]. Parallel to these developments, Casimir-like forces induced by non-equilibrium fluctuations have received a growing attention in the past few years [13][14][15][16][17][18]. Interest in this extension of the Casimir effect lies in the intrinsic long-range nature of correlations in