This paper demonstrates the implementation of chiral quantum optics using a low-noise quantum dot in an open microcavity. The researchers demonstrate non-reciprocal absorption of single photons, creating a single-photon diode with a non-reciprocity as high as 10.7 dB. This is achieved by tuning the photon-emitter coupling to the optimal condition (β = 0.5). The quantum nature of the nonlinearity is validated by observing photon bunching, demonstrating that the single-photon component is largely removed.

Nadia O. Antoniadis, Natasha Tomm, Tomasz Jakubczyk, Rüdiger Schott, Sascha R. Valentin, Andreas D. Wieck, Arne Ludwig, Richard J. Warburton, Alisa Javadi