Directional quantum-squeezing-enabled nonreciprocal enhancement of entanglement

We theoretically propose how to achieve nonreciprocal enhancement of bipartite and tripartite entanglement using an optomechanical resonator coupled to a nonlinear optical resonator. We find that by our pumping the nonlinear resonator, directional optical squeezing can occur along the pump direction, resulting in an asymmetric detuning and chiral photon interaction between the two resonators. As a result, nonreciprocal enhancement of bipartite and tripartite entanglement can be achieved, exhibiting robustness regarding bath temperature. Specifically, in one direction, bipartite entanglement can be enhanced by about 2 times and tripartite entanglement can be enhanced by about 3.5 times compared with the opposite direction. Our work provides a route to manipulate and enhance nonreciprocal bipartite and tripartite entanglement using directional quantum squeezing, which may find potential applications in constructing chiral quantum networks.