Controllable single-photon nonreciprocal transmission in a cavity optomechanical system with a weak coherent driving

TL;DR

This paper demonstrates controllable nonreciprocal single-photon transmission in a cavity optomechanical system, showing how weak coherent driving can switch between isolation and amplification, with considerations of thermal noise effects.

Contribution

It introduces a method to control single-photon nonreciprocity in an optomechanical system using weak coherent driving, expanding understanding of quantum nonreciprocal devices.

Findings

Achieved transformation from unidirectional isolation to amplification at the single-photon level.

Identified the importance of input-output spectrum comparison for nonreciprocity analysis.

Analyzed the impact of mechanical thermal noise on nonreciprocal transmission.

Abstract

We study the nonreciprocal transmission of a single-photon in a cavity optomechanical system, in which the cavity supports a clockwise and a counter-clockwise circulating optical modes, the mechanical resonator (MR) is excited by a weak coherent driving, and the signal photon is made up of a sequence of pulses with exactly one photon per pulse. We find that, if the input state is a single-photon state, it is insufficient to study the nonreciprocity only from the perspective of the transmission spectrums, since the frequencies where the nonreciprocity happens are far away from the peak frequency of the single-photon. So we show the nonreciprocal transmission behavior by comparing the spectrums of the input and output fields. In our system, we can achieve a transformation of the signal transmission from unidirectional isolation to unidirectional amplification in the single-photon level by changing the amplitude of the weak coherent driving. The effects of the mechanical thermal noise on the single-photon nonreciprocal transmission are also discussed.