Speaker
Description
Extracting useful work from environmental fluctuations—or, equivalently, minimizing the energetic cost of driving a system—has long been a central goal in physics and engineering. This pursuit is inspired by biological systems, such as motor proteins, which achieve directed motion in intrinsically noisy environments. In synthetic settings, however, work extraction typically requires carefully designed control strategies, including feedback protocols, time-dependent confinement, and precise tuning of fluctuation strengths.
A paradigmatic realization is provided by optical-tweezer experiments, where work is performed by translating the center of a confining harmonic trap. Here, we extend this framework to an activity-driven odd tracer embedded in either Newtonian or viscoelastic (Maxwell) baths, such as micellar solutions. In odd tracers, the mobility tensor acquires antisymmetric components, giving rise to a transverse response to applied perturbations. Such odd mobility arises in a broad class of systems, including charged tracers in magnetic fields, spinning colloids, chiral active fluids, and biological swimmers in asymmetric environments.
Within this setup, we consider two optical control schemes: an open-loop protocol, in which the active force is not measured, and a closed-loop protocol in which the initial value of the active force is measured prior to the experiment. We identify optimal protocols and the regimes of force configuration, force persistence, environmental relaxation timescales, and odd mobility that determine the energetic cost of control. In particular, we find that conditioning on the magnitude and direction of the initial active force enhances work extraction differently for odd and normal tracers. These findings provide basic design principles for active micromachines in complex biomolecular environments, showing how controlled tuning of activity can enable efficient energy conversion.
