Non-Reciprocal Transmission and Reflection of a Chirally-Coupled Quantum Dot
Submitted to Physical Review X , (2018)
We report non-reciprocal transmission and reflection for quantum dot exciton spins coupled to nanophotonic waveguides. A clear dependence on propagation direction is found for a chirally-coupled quantum dot, with spin up and spin down exciton spins coupling to the left and right propagation directions respectively. The reflection signal shows an opposite trend to the transmission, which a numerical model indicates is due to direction-selective saturation of the dot. The chiral spin-photon interface we demonstrate breaks reciprocity of the system, and opens the way to spin-based quantum optical components such as optical diodes and circulators in a chip-based solid-state environment.