Brownian particles in nonequilibrium baths

Introduction

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.

Idealized Thermal Baths

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 a description, however, is only valid when the bath relaxation time is much faster than typical time scales of the system.

Nonequilibrium Effects

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 of Novel Behaviors

Examples include:

• Particle oscillations inside moving optical traps
• Fastened hopping dynamics across potential barriers
• Up to 100-fold enhanced rotational diffusion of drifting particles
• Presence of about one-million-fold increased Magnus forces

Proposed Experiments

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 effects for applications.

Investigation Focus

In those experiments, we will investigate how nonequilibrium surroundings affect:

1. Erasure processes of logical information
2. Modification of the design of optimal finite time protocols

Microscopic Engine Construction

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.

Selection of Examples

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 to provide possible overlaps beyond the field of soft condensed matter.