Condensed Matter Physics Seminar: Rosalba Garcia Milan

Abstract: Active matter is driven out of equilibrium at the local, microscopic scale. Active particles sustain a non-equilibrium state by constantly turning a local energy supply into mechanical work, leading to a constant production of entropy. The entropy production rate is thus a key observable in active systems, as it quantifies how far from equilibrium a system is, as well as it captures its time irreversibility.

In this talk, I will present a field-theoretic method to calculate the entropy production rate analytically [1]. I will show how to cast the microscopic dynamics in the form of a master or Fokker-Planck equation in a Doi-Peliti field theory, and how to use this framework to determine general formulae for the entropy production of interacting self-propelled particles. As opposed to coarse-grained descriptions of active systems, the advantage of a Doi-Peliti field theory is that it retains the microscopic details, which are crucial when calculating the entropy production. I will illustrate our method with examples such as a run-and-tumble particle in a confining potential [2], interacting active Brownian particles undergoing motility-induced phase separation [1], and diffusive particles with non-reciprocal interactions [3].

[1] Pruessner, RGM, Field theories of active particle systems and their entropy production, arXiv:2211.11906.
[2] RGM, Pruessner, Run-and-tumble motion in a harmonic potential: field theory and entropy production, J. Stat. Mech. 2021, 063203 (2021).
[3] Zhang, RGM, Entropy production of non-reciprocal interactions, Phys. Rev. Research 5, L022033 (2023).