Engineering strong chiral light-matter interactions in a waveguide-coupled nanocavity

TL;DR

This paper demonstrates numerically that embedding spin-dependent quantum emitters in a waveguide-coupled nanocavity with orthogonal modes can achieve highly efficient, chiral light-matter interactions suitable for quantum networks.

Contribution

The work introduces a cavity design supporting near-degenerate orthogonal modes that enable strong, directional chiral coupling with high efficiency and light-matter interaction strength.

Findings

Achieved near-unity chiral contrast in the cavity design.

Demonstrated efficient waveguide coupling with $eta > 0.95$.

Enhanced light-matter interaction with Purcell factor $F_P > 70$.

Abstract

Spin-dependent, directional light-matter interactions form the basis of chiral quantum networks. In the solid state, quantum emitters commonly possess circularly polarised optical transitions with spin-dependent handedness. We demonstrate numerically that spin-dependent chiral coupling can be realised by embedding such an emitter in a waveguide-coupled nanocavity, which supports two near-degenerate, orthogonally-polarised cavity modes. The chiral behaviour arises due to direction-dependent interference between the cavity modes upon coupling to two single-mode output waveguides. Notably, an experimentally realistic cavity design simultaneously supports near-unity chiral contrast, efficient ($\beta > 0.95$) waveguide coupling and enhanced light-matter interaction strength (Purcell factor $F_P > 70$). In combination, these parameters could enable the development of highly coherent spin-photon interfaces, ready for integration into nanophotonic circuits.