A chiral topological add-drop filter for integrated quantum photonic circuits

TL;DR

This paper demonstrates a topologically protected, chiral quantum photonic device that enables wavelength-selective routing and spin-dependent light-matter interactions, advancing integrated quantum photonic circuit technology.

Contribution

It introduces a novel topological add-drop filter with spin-dependent chiral light-matter interaction using quantum dots in a valley-Hall photonic crystal.

Findings

Achieved wavelength-selective routing protected by topology

Demonstrated spin-dependent coupling at a chiral point

Enabled potential for chiral quantum optical devices

Abstract

The integration of quantum emitters within topological nano-photonic devices opens up new avenues for the control of light-matter interactions at the single photon level. Here, we realise a spin-dependent, chiral light-matter interface using individual semiconductor quantum dots embedded in a topological add-drop filter. The filter is imprinted within a valley-Hall photonic crystal (PhC) membrane and comprises a resonator evanescently coupled to a pair of access waveguides. We show that the longitudinal modes of the resonator enable the filter to perform wavelength-selective routing of light, protected by the underlying topology. Furthermore, we demonstrate that for a quantum dot located at a chiral point in the resonator, selective coupling occurs between well-defined spin states and specific output ports of the topological device. This behaviour is fundamental to the operation of chiral devices such as a quantum optical circulator. Our device therefore represents a topologically-protected building block with potential to play an enabling role in the development of chiral integrated quantum photonic circuits.