Related Experiment Video
Updated: Jul 26, 2025

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Nonequilibrium currents in stochastic field theories: A geometric insight
1Université Paris-Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France and DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom.
Abstract:
We introduce a formalism to study nonequilibrium steady-state probability currents in stochastic field theories. We show that generalizing the exterior derivative to functional spaces allows identification of the subspaces in which the system undergoes local rotations. In turn, this allows prediction of the counterparts in the real, physical space of these abstract probability currents. The results are presented for the case of the Active Model B undergoing motility-induced phase separation, which is known to be out of equilibrium but whose steady-state currents have not yet been observed, as well as for the Kardar-Parisi-Zhang equation. We locate and measure these currents and show that they manifest in real space as propagating modes localized in regions with nonvanishing gradients of the fields.
Related Concept Videos
Carrier Transport
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
Electromagnetic Fields
However, the observation of...
Induced Electric Fields: Applications
Divergence and Curl of Electric Field
Magnetostatic Boundary Conditions
Divergence and Stokes' Theorems

