Berlin 2018 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 9: Statistical Physics far from Thermal Equilibrium

DY 9.5: Vortrag

Montag, 12. März 2018, 11:00–11:15, BH-N 334

Quantum heat engines and laser cooling: A study beyond the weak coupling and Markovian approximations — •Sebastian Restrepo¹, Javier Cerrillo¹, Philipp Strasberg², and Gernot Schaller¹ — ¹Institut für Theoretische Physik, Technische Universität Berlin, Germany — ²Complex Systems and Statistical Mechanics, University of Luxembourg, Luxembourg

We study a periodically driven thermal machine beyond the weak coupling and Markovian approximations by combining a collective coordinate mapping with Floquet theory and full counting statistics. We identify a collective degree of freedom in the reservoir that is included as part of an enlarged supersystem to take strong coupling and non-Markovian effects into account. The periodicity of our extended model is exploited using Floquet theory to obtain a master equation with full counting statistics methods permitting a thermodynamic analysis. The formalism is applied to a thermal machine consisting of a driven two-level system coupled to two reservoirs at different temperatures with one of the couplings considered time-dependent. In the weak-coupling regime, the setup can switch between the operational modes of a heat engine or a refrigerator directly. As the coupling is increased, we identify four different operation regimes and see the eventual disappearance of the refrigerator. We observe that the efficiency and coefficient of performance decrease for stronger couplings. Taking the limit of a single reservoir, our model is able to replicate the setup of state preparation in laser cooling of trapped ions.