Algebraic approach to a nonadiabatic coupled Otto cycle

Algebraic methods for solving time-dependent Hamiltonians are used to investigate the performance of quantum thermal machines. We thermodynamic properties an engine formed by two coupled qubits, performing Otto cycle. The interaction occurs with baths at different temperatures, while work is associated arbitrary magnetic field that varies in intensity and direction. For coupling, we consider 1D isotropic Heisenberg model, which allows us describe system means irreducible representation $\mathrm{su}(2)$ Lie algebra within triplet subspace. also inspect settings temperatures frequencies cycle, corresponding operation regimes. how these regimes can change speed protocol. Finally, compare weak strong coupling regimes, conclude case efficiency optimal surpass value classical low heat baths, show losses due friction reduced limit.