Quantum field heat engine powered by phonon-photon interactions

We present a quantum heat engine based on a cavity with two oscillating mirrors that confine a quantum field. The engine performs an Otto cycle during which the walls and a field mode, together representing the working substance of the engine, interact via a nonlinear Hamiltonian. Resonances between the frequencies of the cavity mode and the walls allow one to transfer heat from the hot and the cold bath by exploiting the conversion between phononic and photonic excitations. We study the time evolution of the system and show that net work can be extracted after a full cycle. We evaluate the efficiency of the process.