Brownian particles in nonequilibrium baths

Obiettivo

The power of thermodynamics comes at the expense of certain assumptions and idealizations. An important premise is the concept of a thermal bath which is in contact with the examined system. Typically, such baths are idealized as an infinite reservoir of heat that remains in equilibrium regardless of whether the system in contact is in equilibrium or not. Such description, however, is only valid when the bath relaxation time is much faster than typical time scales of the system. Otherwise, a driven system excites the bath out of equilibrium and will interact with nonequilibrium fluctuations. Recent experiments using colloidal particles within viscoelastic baths, whose relaxation times are comparable to colloidal timescales, have revealed surprising and only poorly understood novel behaviors which are attributed to the nonequilibrium properties of the bath. Examples include particle oscillations inside moving optical traps, a fastened hopping dynamics across potential barriers, an up to 100-fold enhanced rotational diffusion of drifting particles, but also the presence of about one-million-fold increased Magnus forces. Here, we propose a series of novel experiments aiming to uncover the impact of a non-equilibrated bath on the behavior of externally driven colloidal particles but also to exploit such effect for applications. In those experiments we will investigate how nonequilibrium surroundings affect erasure processes of logical information or modify the design of optimal finite time protocols. In addition, we will construct an unprecedented microscopic engine which – unlike conventional heat engines – is not operated between two heat baths but which is periodically coupled to nonequilibrium baths with different relaxation times. The selection of the examples being pursued within this proposal has been chosen not only to demonstrate the manifold consequences of nonequilibrium baths but also provide possible overlaps beyond the field of soft condensed matter.