Dynamics and steady states of a tracer particle in a confined critical fluid

The dynamics and the steady states of a point-like tracer particle immersed in confined critical fluid are studied. is modeled field-theoretically terms an order parameter (concentration or density field) obeying dissipative conservative equilibrium (non-)symmetry-breaking boundary conditions. tracer, which represents, e.g., colloidal particle, interacts with by locally modifying its chemical potential correlations. coupling between gives rise to nonlinear non-Markovian dynamics, investigated here analytically via numerical simulations for one-dimensional system. From coupled Langevin equations tracer-fluid system we derive effective Fokker-Planck equation means adiabatic elimination as well perturbation theory within weak-coupling approximation. found be governed fluctuation-induced (Casimir) potential, spatially dependent mobility, (multiplicative) noise, characteristics depend on interaction steady-state distribution typically inhomogeneous. Notably, when detailed balance broken, driving temporally correlated noise can induce attraction towards boundary.