Thermodynamics performance optimization of a Lipkin-Meshkov-Glick heat engine model with anisotropy
Abstract
Heat engine implementation in the atomic or nanoscale involves thermodynamic and quantum properties of the working substance. Interest in the optimization of these quantum effects is driven by the rise of electronic devices in the nanoscale and the search for devices that can power quantum technologies in the future. It has been shown that quantum heat engines outperform their classical counterparts, and several physically realizable engines have been constructed using quantized spin models. We investigate the performance of the quantum heat engine following a Carnot cycle with four strokes – two reversible isothermal and isomagnetic steps, connected to constant temperature heat baths. The working medium of this quantum device is the Lipkin-Meshkov-Glick (LMG) model consists of two or three spins. In this work, anisotropy is introduced to the working medium. The energy eigenstates are calculated by solving Schrödinger’s equation and the thermodynamic performance of each process is obtained using the canonical ensemble. The effect of anisotropy in the operation of the engine is seen in the energy eigenvalues as work production is maximized for specific anisotropy and applied magnetic field strengths. Optimization of the applied magnetic field for a given anisotropy and the change in the adjacent energy level spacing determines the efficiency of a quantum Carnot heat engine.
