Finite-time performance of quantum Otto refrigerators driven by a squeezed reservoir

Abstract

We consider a finite-time quantum Otto refrigerator that consists of two isochoric (thermal-contact) processes, where the working substance is alternatively coupled to a cold squeezed reservoir and a hot thermal reservoir, and two unitary driven strokes, where the working substance is isolated from these two reservoirs and its von Neumann entropy is kept constant. Both quantum inner friction and coherence are generated along the finite-time driven strokes, and coherence cannot be fully erased along an isochoric stroke. We demonstrate that, either in presence or in absence of reservoir squeezing, speeding up the machine may lead to an increase in both average cooling rate and thermodynamic coefficient of performance, with no sacrifice of machine stability. Our results also show that reservoir squeezing significantly enhances the performance by improving both the coefficient of performance and the cooling rate, and it enables higher stability by damping the fluctuations of cooling rate and coefficient of performance.