Lipkin-Meshkov-Glick model in a quantum Otto cycle

The Lipkin-Meshkov-Glick model of two anisotropically interacting spins in a magnetic field is proposed as a working substance of a quantum Otto engine to explore and exploit the anisotropy effects for the optimization of engine operation. Three different cases for the adiabatic branches of the cycle have been considered. In the first two cases, either the magnetic field or coupling strength are changed while, in the third case, both the magnetic field and the coupling strength are changed by the same ratio. The system parameters for which the engine can operate similar to or dramatically different from the engines of non-interacting spins or of coupled spins with Ising model or isotropic XY model interactions are determined. In particular, the role of anisotropy to enhance cooperative work, and to optimize maximum work with high efficiency, as well as to operate the engine near the Carnot bound are revealed.