title: Dephasing and dissipation in qubit thermodynamics.
abstract: We analyze the stochastic evolution and dephasing of a qubit within the quantum jump approach. It allows one to treat individual realizations of inelastic processes, and in this way it provides solutions, for instance, to problems in quantum thermodynamics and distributions in statistical mechanics. We demonstrate that dephasing and relaxation of the qubit render the Jarzynski and Crooks fluctuation relations (FRs) of nonequilibrium thermodynamics intact. On the contrary, the standard two-measurement protocol, taking into account only the fluctuations of the internal energy U, leads to deviations in FRs under the same conditions. We relate the average 〈e(-βU)〉 (where β is the inverse temperature) with the qubit's relaxation and dephasing rates in the weak dissipation limit and discuss this relationship for different mechanisms of decoherence.
authors.affiliation: Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, 00076 Aalto, Finland.
authors.forename: J P
authors.initials: JP
authors.lastname: Pekola
authors.affiliation: Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Masuyama
authors.affiliation: Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan.|RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Physics Department, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway.
authors.forename: J
authors.initials: J
authors.lastname: Bergli
authors.affiliation: Physics Department, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway.|A. F. Ioffe Physico-Technical Institute RAS, 194021 St. Petersburg, Russian Federation.
authors.forename: Y M
authors.initials: YM
authors.lastname: Galperin