Berlin 2018 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 71: Poster: Noneq. Stat. Phys., Stoch. Thermo, Brownian Dyn.
DY 71.7: Poster
Thursday, March 15, 2018, 15:30–18:00, Poster A
Quantum heat engines and laser cooling: Floquet theory beyond the Born-Markov approximation — •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 combine the formalism of Floquet theory, full counting statistics and a collective coordinate mapping to access the dynamics and thermodynamics of a periodically driven thermal machine beyond the conventional Born-Markov approximation. We identify a collective degree of freedom in the reservoir that is included as part of the original system and that is responsible for the strong coupling and non-Markovian effects. The periodicity of our model is exploited using Floquet theory to obtain a master equation for the newly defined supersystem 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 non-Markovian regime the thermal machine can act either as a heat engine or a refrigerator. As the coupling is increased, we identify four different operation regimes and see the eventual disappearing 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.