Coherent-feedback-induced photon blockade and optical bistability by an optomechanical controller

TL;DR

This paper demonstrates that a coherent feedback control strategy can induce strong nonlinear quantum effects, such as photon blockade and optical bistability, in optomechanical systems that are otherwise weakly coupled, expanding possibilities for quantum engineering.

Contribution

The study introduces a coherent feedback control method that transfers and amplifies quantum nonlinearity, enabling observation of photon blockade in weakly coupled optomechanical systems.

Findings

Strong photon blockade observed under weak coupling conditions

Coherent feedback induces two-photon and multiphoton tunneling

Enhanced quantum nonlinearity in linear and optomechanical cavities

Abstract

It is well-known that some nonlinear phenomena such as strong photon blockade are hard to be observed in optomechanical system with current experimental technology. Here, we present a coherent feedback control strategy in which a linear cavity is coherently controlled by an optomechanical controller in a feedback manner. The coherent feedback loop transfers and enhances quantum nonlinearity from the controller to the controlled cavity, which makes it possible to observe strong nonlinear effects in either linear cavity or optomechanical cavity. More interestingly, we find that the strong photon blockade under single-photon optomechanical weak coupling condition could be observed in the quantum regime. Additionally, the coherent feedback loop leads to two-photon and multiphoton tunnelings for the controlled linear cavity, which are also typical quantum nonlinear phenomenon. We hope that our work can give new perspectives in engineering nonlinear quantum phenomena.