  Recent work by Teifel and Mahler [Eur. Phys. J. B 75, 275 (2010)] raises
legitimate concerns regarding the validity of quantum nonequilibrium work
relations in processes involving moving hard walls. We study this issue in the
context of the rapidly expanding one-dimensional quantum piston. Utilizing
exact solutions of the time-dependent Schrodinger equation, we find that the
evolution of the wave function can be decomposed into static and dynamic
components, which have simple semiclassical interpretations in terms of
particle-piston collisions. We show that nonequilibrium work relations remains
valid at any finite piston speed, provided both components are included, and we
study explicitly the work distribution for this model system.
