  We study the reversible crossover between stable and bistable phases of an
over-damped Brownian bead inside an optical piston. The interaction potentials
are solved developing a method based on Kramers' theory that exploits the
statistical properties of the stochastic motion of the bead. We evaluate
precisely the energy balance of the crossover. We show that the deformation of
the optical potentials induced by the compression of the piston is related to a
production of heat which measures the non-adiabatic character of the crossover.
This reveals how specific thermodynamic processes can be designed and
controlled with a high level of precision by tailoring the optical landscapes
of the piston.
