Quantum thermal machine regimes in the transverse-field Ising model
Phys. Rev. A 111, 062213 – Published 17 June, 2025
DOI: https://doi.org/10.1103/jthm-7c2j
Abstract
We identify and interpret the possible quantum thermal machine regimes with a transverse-field Ising model as the working substance. In general, understanding the emergence of such regimes in a many-body quantum system is challenging due to the dependence on the many energy levels in the system. By considering infinitesimal work strokes, we can understand the operation from equilibrium properties of the system. We find that infinitesimal work strokes enable both heat engine and accelerator operation, with the output and boundaries of operation described by macroscopic properties of the system, in particular, the net transverse magnetization. At low temperatures, the regimes of operation and performance can be understood from the behavior of low-energy excitations in the system, while at high temperatures an expansion of the free energy in powers of inverse temperature describes the operation. The understanding generalizes to larger work strokes when the temperature difference between the hot and cold reservoirs is large. For hot and cold reservoirs close in temperature, a sufficiently large work stroke can enable refrigerator and heater regimes. Our results and method of analysis will prove useful in understanding the possible regimes of operation of quantum many-body thermal machines more generally.
