Quantum engines and refrigerators

X. L. Huang, Xin-Ya Niu, Xiao‐Ming Xiu +1 more

Haoguang 浩广 Liu 刘

Abstract We consider a quantum endoreversible Otto engine cycle and its inverse operation-Otto refrigeration cycle, employing two-level systems as the working substance and operating in dual-squeezed reservoirs. We demonstrate that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum χ criterion will degenerate to η − = η C/(2 – η C) and ε − = ( 9 + 8 ε C − 3 ) / 2 when symmetric squeezing is satisfied, respectively. We also investigated the influences of squeezing degree on the performance optimization of quantum Otto heat engines at the maximum work output and refrigerators at the maximum χ criterion. These analytical results show that the efficiency of heat engines at maximum work output and the coefficient of performance for refrigerators at the maximum χ criterion can be improved, reduced or even inhibited in asymmetric squeezing. Furthermore, we also find that the efficiency of quantum Otto heat engines at maximum work output is lower than that obtained from the Otto heat engines based on a single harmonic oscillator system. However, the coefficient of performance of the corresponding refrigerator is higher.

Gershon Kurizki, Abraham G. Kofman

Étienne Jussiau, Sreenath K. Manikandan, Andrew N. Jordan

Aslı Tuncer, Batu Yalçın

We investigate a quantum Otto engine with a quantum Ising spin glass as the working medium to explore the scaling behavior of work output and thermodynamic performance concerning system size, particularly near the critical point. Specifically, we explore the two operating modes of the Otto engine, namely the heat engine and refrigerator modes. We observe a double-peaked structure in the heat engine regime, leading to superlinear scaling in both work output and thermodynamic performance near the critical point. Additionally, in the refrigerator regime, superlinear scaling in refrigerator efficiency can be achieved at high and low temperatures, significantly outperforming models with uniform Ising interactions. These findings suggest that disorder and frustration in quantum Ising spin-glass systems could significantly impact thermodynamic performance in quantum heat engines and refrigerators, potentially opening up new avenues for improvement.