$\mathcal{PT}$-symmetric effects in measurement-based quantum thermal machines

Abstract

Measurement-based quantum thermal machines are fascinating models of thermodynamic cycles where measurement protocols play an important role in the performance and functioning of the cycle. Despite theoretical advances, interesting experimental implementations have been reported. Here we move a step further by considering in this class of cycle $\mathcal{PT}$-symmetric non-Hermitian Hamiltonians and their implications in quantum thermal machines fueled by generalized measurements. We present theoretical results indicating that $\mathcal{PT}$-symmetric effects and measurement protocols are related along the cycle. Furthermore, tuning the parameters suitably it is possible to improve the power output (engine configuration) and the cooling rate (refrigerator configuration), operating in the Otto limit, in a finite-time cycle that satisfies the quantum adiabatic theorem. Our model also allows switching the configuration of the cycle, engine, or refrigerator, depending on the strength of the measurement protocol.