Two sources of quantum deviations from Jarzynski's celebrated classical relation between the free energy change and the distribution of work are analyzed using an exactly solvable harmonic model: Quantum dynamics retains the Gaussian profile of the distribution and merely gives rise to analytic corrections in $\hslash$, whereas quantum measurements (wave function collapse) induce extended power-law tails which fundamentally alter the distribution. These results may be observed in quantum information processing and in experiments involving mechanically or optically driven single quantum objects.

• Received 21 January 2004

DOI:https://doi.org/10.1103/PhysRevLett.93.048302