Continuous measurement boosted adiabatic quantum thermal machines

We present a unified approach to study continuous measurement-based quantum thermal machines in static as well as adiabatically driven systems. We investigate both steady-state and transient dynamics for the time-independent case. In the adiabatically driven case, we show how measurement-based thermodynamic quantities can be attributed geometric characteristics. We also provide the appropriate definition for heat transfer and dissipation owing to continuous measurement in the presence and absence of adiabatic driving. We illustrate the aforementioned ideas and study the phenomenon of refrigeration in two different paradigmatic examples: a coupled quantum dot and a coupled qubit system, both undergoing continuous measurement and slow driving. In the time-independent case, we show that quantum coherence can improve the cooling power of measurement-based quantum refrigerators. Exclusively for the case of coupled qubits, we consider linear as well as nonlinear system-bath couplings. We observe that nonlinear coupling produces cooling effects in certain regimes where otherwise heating is expected. In the adiabatically driven case, we observe that quantum measurement can provide significant boost to the power of adiabatic quantum refrigerators. We also observe that the obtained boost can be larger than the sum of power due to individual effects. The measurement-based refrigerators can have similar or better coefficient of performance in the driven case compared to the static one in the regime where heat extraction is maximum. Our results have potential significance for future application in devices ranging from measurement-based quantum thermal machines to refrigeration in quantum processing networks.