Efficiency of the non-maximally entangled quantum Otto engine

Abstract

We generalized the maximally entangled Hamiltonian of the isotropic Heisenberg XX model with two spin-1/2 particles to the case of non-maximal entanglement parametrized by the degree of non-maximality 0 < n < 1. The thermal concurrence as the function of the degree of non-maximality in the entanglement at different values of the exchange parameter is calculated. We analyzed the efficiency
of the quantum Otto engine for different scenarios of exchange parameter regimes and the degree of maximal entanglement between the spin states. We showed that it is possible to run the quantum Otto engine using non-maximally entangled states and achieve higher efficiencies by controlling the exchange parameter value with respect to a critical value Jc and this feature also depends on the degree of non-maximal entanglement n 6= 1. This result may be useful for harnessing the non-maximal entanglement in quantum heat engine for optimizing the operation of quantum devices interacting with heat bath or environment.