Enhanced mechanical entanglement in an optomechanical cavity with a Coulomb interaction

A scheme of a two-mode optomechanical cavity is proposed to investigate the entanglement between two nanomechanical resonators which are coupled by a Coulomb interaction. It is found that the mechanical entanglement can be improved by the Coulomb coupling, and the restriction of environment temperature on the entanglement can be relaxed by strengthening the Coulomb coupling. Additionally, the optomechanically induced transparency in the present scheme can provide a wider transparency frequency range in which the mechanical entanglement is created. The scheme of the enhanced entanglement by the Coulomb interaction is of more convenient controllability only by adjusting the bias gate voltage.