Hall 123

Strongly coupled quantum Otto cycle with single qubit bath

Sagnik Chakraborty

Department of Theoretical Physics, Complutense University of Madrid, Spain

We discuss a model of a closed quantum evolution of two qubits where the joint Hamiltonian is so chosen
such that one of the qubits acts as a bath and thermalizes the other qubit which is acting as the system.
The corresponding exact master equation for the system is derived. Interestingly, for a specific choice of
parameters the master equation takes the Gorini-Kossakowski-Lindblad-Sudarshan (GKLS) form, with constant
coefficients representing pumping and damping of a single qubit system. Based on this model we construct an
Otto cycle connected to a single qubit bath and study its thermodynamic properties. Our analysis goes beyond
the conventional weak coupling scenario and illustrates the effects of finite baths, including non-Markovianity.
We find closed form expressions for efficiency (coefficient of performance), power (cooling power) for the heat
engine regime (refrigerator regime), and for different modifications of the joint Hamiltonian.

Paper link: journals.aps.org/pre/pdf/10.1103/PhysRevE.106.064133