Abstract

At high temperature, thermal decoherence dominates so that the entanglement of quantum states is difficult to preserve. Realizing high-temperature entanglement is, therefore, a challenge to the current quantum technologies. Here, we demonstrate that considerable degrees of continuous-variable entanglement between two macroscopic objects placed in an environment of high temperature can be created through the medium of properly prepared light fields coupled to them. There are two steps to make such entanglement. First, by pumping an optical cavity field pressuring on a mechanical resonator as a macroscopic object with a blue-detuned drive field, the competition between the induced squeezing effect due to the blue-detuned drive and the existing thermal decoherence leads to a stable entanglement between the cavity field and mechanical resonator. A condition for realizing field-resonator entanglement is determined at any temperature and for any given optomechanical system. The second step is to entangle two distant mechanical resonators through a procedure of entanglement swapping. A detailed example of illustrating this entanglement swapping shows that a considerable degree of entanglement between the two mechanical resonators can be created. The current study proposes a route toward high-temperature entanglement in a realistic physical system.