$\mathcal{PT}$ symmetric phase transition and single-photon transmission in an optical trimmer system

TL;DR

This paper investigates the phase transition in an optical trimmer system with $ ext{PT}$ symmetry, analyzing single-photon transmission behaviors and identifying signatures of symmetry breaking for potential photonic device applications.

Contribution

It provides an analytical study of $ ext{PT}$ symmetric phase transition and reveals distinct single-photon transmission mechanisms in different phases.

Findings

Non-periodical dynamics as a signature of phase transition

Unidirectional single-photon transmission in both phases

Different physical mechanisms underlying transmission behaviors

Abstract

The parity-time ($\mathcal{PT}$) symmetric structures have exhibited potential applications in developing various robust quantum devices. In an optical trimmer with balanced loss and gain, we analytically study the $\mathcal{PT}$ symmetric phase transition by investigating the spontaneous symmetric breaking. We also illustrate the single-photon transmission behaviors in both of the $\mathcal{PT}$ symmetric and $\mathcal{PT}$ symmetry broken phases. We find (i) the non-periodical dynamics of single-photon transmission in the $\mathcal{PT}$ symmetry broken phase instead of $\mathcal{PT}$ symmetric phase can be regarded as a signature of phase transition; and (ii) it shows unidirectional single-photon transmission behavior in both of the phases but comes from different underlying physical mechanisms. The obtained results may be useful to implement the photonic devices based on coupled-cavity system.