Nonlinear interactions and quantum entanglement for collective fields in near-resonantly driven systems

This paper proposes a novel form of multimode nonlinear interactions by using a near-resonantly dressed atomic ensemble in an optical cavity. Due to quantum interference, a pair of collective fields come into the bilinear interactions, whose strengths are proportional to the population difference between dressed states which are coupled to the collective fields. By such an interaction, it is possible to obtain perfect multimode squeezing and collective Einstein–Podolsky–Rosen (EPR) entanglement in the cavity output.