The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform

Bassano Vacchini - One of the best experts on this subject based on the ideXlab platform.

  • Nonequilibrium quantum bounds to Landauer's principle: Tightness and effectiveness
    Physical Review A, 2017
    Co-Authors: Steve Campbell, Giacomo Guarnieri, Mauro Paternostro, Bassano Vacchini
    Abstract:

    We assess two different non-equilibrium quantum Landauer bounds: the traditional approach based on the change in entropy, referred to as the `entropic bound', and one based on the details of the dynamical map, referred to as the `thermodynamic bound'. By first restricting to a simple exactly solvable model of a single two level system coupled to a finite dimensional thermal environment and by exploiting an excitation preserving interaction, we establish the dominant role played by the population terms in dictating the tightness of these bounds with respect to the dissipated heat, and clearly establish that coherences only affect the entropic bound. Furthermore, we show that sharp boundaries between the relative performance of the two quantities emerge, and find that there are clear instances where both approaches return a bound weaker than Clausius' Statement of the second law, rendering them ineffective. Finally we show that our results extend to generic interaction terms.

Eric Lutz - One of the best experts on this subject based on the ideXlab platform.

  • Efficiency of heat engines coupled to nonequilibrium reservoirs
    EPL (Europhysics Letters), 2014
    Co-Authors: Obinna Abah, Eric Lutz
    Abstract:

    We consider quantum heat engines that operate between nonequilibrium stationary reservoirs. We evaluate their maximum efficiency from the positivity of the entropy production and show that it can be expressed in terms of an effective temperature that depends on the nature of the reservoirs. We further compute the efficiency at maximum power for different kinds of engineered reservoirs and derive a nonequilibrium generalization of the Clausius Statement of the second law.

Steve Campbell - One of the best experts on this subject based on the ideXlab platform.

  • Nonequilibrium quantum bounds to Landauer's principle: Tightness and effectiveness
    Physical Review A, 2017
    Co-Authors: Steve Campbell, Giacomo Guarnieri, Mauro Paternostro, Bassano Vacchini
    Abstract:

    We assess two different non-equilibrium quantum Landauer bounds: the traditional approach based on the change in entropy, referred to as the `entropic bound', and one based on the details of the dynamical map, referred to as the `thermodynamic bound'. By first restricting to a simple exactly solvable model of a single two level system coupled to a finite dimensional thermal environment and by exploiting an excitation preserving interaction, we establish the dominant role played by the population terms in dictating the tightness of these bounds with respect to the dissipated heat, and clearly establish that coherences only affect the entropic bound. Furthermore, we show that sharp boundaries between the relative performance of the two quantities emerge, and find that there are clear instances where both approaches return a bound weaker than Clausius' Statement of the second law, rendering them ineffective. Finally we show that our results extend to generic interaction terms.

Ronnie Kosloff - One of the best experts on this subject based on the ideXlab platform.

  • The local approach to quantum transport may violate the second law of thermodynamics
    EPL (Europhysics Letters), 2014
    Co-Authors: Amikam Levy, Ronnie Kosloff
    Abstract:

    Clausius Statement of the second law of thermodynamics reads: Heat will flow spontaneously from a hot to cold reservoir. This Statement should hold for transport of energy through a quantum network composed of small subsystems each coupled to a heat reservoir. When the coupling between nodes is small, it seems reasonable to construct a local master equation for each node in contact with the local reservoir. The energy transport through the network is evaluated by calculating the energy flux after the individual nodes are coupled. We show by analyzing the most simple network composed of two quantum nodes coupled to a hot and cold reservoir, that the local description can result in heat flowing from cold to hot reservoirs, even in the limit of vanishing coupling between the nodes. A global derivation of the master equation which prediagonalizes the total network Hamiltonian and within this framework derives the master equation, is always consistent with the second law of thermodynamics.

Obinna Abah - One of the best experts on this subject based on the ideXlab platform.

  • Efficiency of heat engines coupled to nonequilibrium reservoirs
    EPL (Europhysics Letters), 2014
    Co-Authors: Obinna Abah, Eric Lutz
    Abstract:

    We consider quantum heat engines that operate between nonequilibrium stationary reservoirs. We evaluate their maximum efficiency from the positivity of the entropy production and show that it can be expressed in terms of an effective temperature that depends on the nature of the reservoirs. We further compute the efficiency at maximum power for different kinds of engineered reservoirs and derive a nonequilibrium generalization of the Clausius Statement of the second law.