Nonreciprocal single-photon frequency converter via multiple semi-infinite coupled-resonator waveguides

TL;DR

This paper proposes a method for nonreciprocal single-photon frequency conversion using coupled-resonator waveguides and optomechanical interactions, enabling dynamic control and potential applications in quantum networks.

Contribution

It introduces a novel scheme for nonreciprocal frequency conversion and circulators for single photons using multiple semi-infinite coupled-resonator waveguides with optomechanical coupling.

Findings

Demonstrated nonreciprocal frequency conversion of single photons.

Designed two types of single-photon circulators with different mechanical modes.

Identified optimal conditions for breaking time-reversal symmetry.

Abstract

We propose to construct a nonreciprocal single-photon frequency converter via multiple semi-infinite coupled-resonator waveguides (CRWs). We first demonstrate that the frequency of a single photon can be converted nonreciprocally through two CRWs, which are coupled indirectly by optomechanical interactions with two nondegenerate mechanical modes. Based on such nonreciprocity, two different single-photon circulators are proposed in the T-shaped waveguides consisting of three semi-infinite CRWs, which are coupled in pairwise by optomechanical interactions. One circulator is proposed by using two nondegenerate mechanical modes and the other one is proposed by using three nondegenerate mechanical modes. Nonreciprocal single-photon frequency conversion is induced by breaking the time-reversal symmetry, and the optimal conditions for nonreciprocal frequency conversion are obtained. These proposals can be used to realize nonreciprocal frequency conversion of single photons in any two distinctive waveguides with different frequencies and they can allow for dynamic control of the direction of frequency conversion by tuning the phases of external driving lasers, which may have versatile applications in hybrid quantum networks.