Quantum Nonlinear Nonreciprocity in a Cavity-Coupled Quantum Dot–Metal Nanoparticle Hybrid System

Optical nonreciprocity (ONR) plays an important role in laser technique, optical communications, quantum information, etc. Realizing ONR at the quantum level of few photons or single photons is also essential for quantum communications or quantum networks. In this work, we propose a hybrid configuration composed of a quantum dot–metallic nanoparticle (QD-MNP) composite in a ring cavity to achieve ONR at the few-photon level via optical bistability. With the surface plasmon effect of the MNP, the bistable property and regime of photons producing ONR in an asymmetric ring cavity including a QD and an MNP inside can be significantly improved in comparison with the case of a single QD. By using the bistability effect, giant ONR can be achieved in an optimal window of numbers of input photons. The detuning and the coupling strength coefficients of the hybrid system can be adjusted and utilized to optimize the performance of the quantum nonreciprocity. This work may find promising applications in quantum nonreciprocal devices and photonic quantum circuits.