Active matter: quantifying the departure from equilibrium

Abstract

Active matter systems are driven out of equilibrium at the level of individual constituents. One widely studied class are systems of athermal particles that move under the combined influence of interparticle interactions and self-propulsions, with the latter evolving according to the Ornstein-Uhlenbeck stochastic process. Intuitively, these so-called active Ornstein-Uhlenbeck particles (AOUPs) systems are farther from equilibrium for longer self-propulsion persistence times. Quantitatively, this is confirmed by the increasing equal-time velocity correlations (which are trivial in equilibrium) and by the increasing violation of the Einstein relation between the self-diffusion and mobility coefficients. In contrast, the entropy production rate, calculated from the ratio of the probabilities of the position space trajectory and its time-reversed counterpart, has a non-monotonic dependence on the persistence time. Thus, it does not properly quantify the departure of AOUPs systems from equilibrium.

6 pages, 4 figures

References in corpus (7)

• A self-propelled particle in an external potential: is there an effective temperature?
• Effective Interactions in Active Brownian Suspensions
• Spontaneous velocity alignment in Motility-induced Phase Separation
• Multidimensional Stationary Probability Distribution for Interacting Active Particles
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• Glassy dynamics of athermal self-propelled particles: Computer simulations and a nonequilibrium microscopic theory
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Cited by in corpus (2)

• Effective temperatures in inhomogeneous passive and active bidimensional Brownian particle systems
• The entropy production of an active particle in a box