Related Experiment Video
Updated: Jul 3, 2026

Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Microcanonical quantum fluctuation theorems
Peter Talkner1, Peter Hänggi, Manuel Morillo
1Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany.
Abstract:
Previously derived expressions for the characteristic function of work performed on a quantum system by a classical external force are generalized to arbitrary initial states of the considered system and to Hamiltonians with degenerate spectra. In the particular case of microcanonical initial states, explicit expressions for the characteristic function and the corresponding probability density of work are formulated. Their classical limit as well as their relations to the corresponding canonical expressions are discussed. A fluctuation theorem is derived that expresses the ratio of probabilities of work for a process and its time reversal to the ratio of densities of states of the microcanonical equilibrium systems with corresponding initial and final Hamiltonians. From this Crooks-type fluctuation theorem a relation between entropies of different systems can be derived which does not involve the time-reversed process. This entropy-from-work theorem provides an experimentally accessible way to measure entropies.
Related Concept Videos
The Uncertainty Principle
Calculation of First-Law Quantities II
The de Broglie Wavelength
Propagation of Uncertainty from Random Error
The Quantum-Mechanical Model of an Atom
Propagation of Uncertainty from Systematic Error
