A Proposal For Preparing Mechanical-atomic Entanglement And Mechanical Squeezing

Lately, research on quantum phenomenon in a coupled optical-mechanic system becomes one of the hot spots in quantum optics and quantum information. The investigation on non-classical properties of mechanic oscillator is of profound meaning for accurate measurements, boundary between quantum and classic, and the information processing. Optical pressure in the two-mode cavity driven by light is studied based on the previous research. The mirror at the cavity moves mechanically under the optical pressure, hence, the mirror is equivalent to a quantum harmonic mechanical oscillator. The intrinsic frequency of the cavity varies with the change in the mirror position, thus, the cavity is coupled to the system. Considering the ensemble of a three-level atom located in the cavity, the ensemble is coupled with the cavity, and the ensemble is driven by the external laser. Numerical analysis shows that when the cavity is driven by a red and a blue non harmonic laser, and the frequency and intensity of the ensemble atom laser are properly set, the loss in the cavity results to the two-mode squeezing vacuum between the ensemble and the mechanical oscillator, thus a stable entanglement with the consecutive variation between the two system is achieved. The entanglement is not affected by the cavity loss in our work. And the larger the loss is, the shorter the time of the squeezing vacuum state. In other cases, the loss between the mechanical oscillator and the atom decreases when the cavity loss rises. Taking account of the heating the mechanical oscillator, the numerical results demonstrate that, the entanglement still exists between the oscillator and the atom, though the thermal phonon nth=400, meaning the system is strong in screening the interference. Moreover, the mechanical squeezing could be obtained in the system assisted with atoms when the two cavities are driven by a red non harmonic laser. The present work is favorable to promote the research which concerns the construction of the entanglement between oscillator and atoms and mechanical squeezing.