Designing of quantum thermal machines

The quest for small quantum thermal machines that can supersede their classical counterparts in performance has been an important and vibrant component in the field of quantum thermodynamics. These machines are expected to not only provide a better understanding of the interplay between the concepts from quantum information theory and thermodynamics, but also lead in building efficient quantum technologies. I will present a design of quantum thermal devices (e.g., quantum battery and quantum refrigerator) based on quantum spin models in arbitrary dimensions where the ground and the thermal states are chosen as initial states. We show that their performances are robust against decoherence and impurities which are inevitably present during preparation. Going beyond the usual convention, I will also discuss a measurement-based quantum refrigerator having an arbitrary number of qubits interacted through variable range interaction. I will show that in such a machine, repeated evolution followed by a measurement on the single accessible qubit has potential to reduce the temperature in the rest of the subsystems, thereby demonstrating cooling in the device.