Generalized Rotating-Wave Approximation for the Quantum Rabi Model with Optomechanical Interaction |
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Authors: | Wallace H Montaño Jesús A Maytorena |
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Institution: | Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apartado Postal 2681, Ensenada, Baja California, 22800 México |
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Abstract: | The spectrum of energy and eigenstates of an hybrid cavity optomechanical system, where a cavity field mode interacts with a mechanical mode of a vibrating end mirror via radiation pressure and with a two level atom via electric dipole interaction are investigated. In the spirit of approximations developed for the quantum Rabi model beyond rotating-wave approximation (RWA), the so-called generalized RWA (GRWA) to diagonalize the tripartite Hamiltonian for arbitrary large couplings is implemented. Notably, the GRWA approach still allows to rewrite the hybrid Hamiltonian in a bipartite form, like a Rabi model with dressed atom-field states (polaritons) coupled to mechanical modes through reparametrized coupling strength and Rabi frequency. A more accurate energy spectrum for a wide range of values of the atom-photon and photon–phonon couplings, when compared to the RWA results is found. The fidelity between the numerical eigenstates and its approximated counterparts is also calculated. The degree of polariton-phonon entanglement of the eigenstates presents a non-monotonic behavior as the atom-photon coupling varies, in contrast to the characteristic monotonic increase in the RWA treatment. |
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Keywords: | generalized rotating-wave approximation light-matter interaction quantum Rabi model optomechanics ultrastrong coupling |
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