Efficiency fluctuations of a quantum heat engine
Tobias Denzler, Eric Lutz
Abstract
The efficiency of quantum heat engines is a stochastic quantity owing to the presence of thermal and quantum fluctuations. We here extend the standard two-projective-measurement scheme to derive the efficiency distribution of a quantum Otto engine. We analyze the generic properties of this distribution for scale-invariant driving Hamiltonians which describe a large class of single-particle, many-body, and nonlinear systems. We find that the mean efficiency is equal to the macroscopic efficiency for adiabatic driving. It generally diverges for nonadiabatic driving when no heat is absorbed while work is produced. We further compute the quantum efficiency statistics for an analytically solvable two-level engine and investigate its classical-to-quantum transition.