A semiconductor photon-sorter

TL;DR

This paper demonstrates a novel method for photon sorting using a quantum dot coupled to a cavity, enabling effective single-photon non-linearity to control photon statistics and correlations, advancing optical switching technology.

Contribution

The study introduces a passive single-photon non-linearity using a quantum dot-cavity system to sort photons and generate correlations, a significant step beyond previous approaches.

Findings

Modified photon counting statistics demonstrating photon sorting

Created strong correlations between detection events

Sorted polarization-correlated photons from uncorrelated streams

Abstract

Photons do not interact directly with each other, but conditional control of one beam by another can be achieved with non-linear optical media at high field intensities. It is exceedingly difficult to reach such intensities at the single photon level but proposals have been made to obtain effective interactions by scattering photons from single transitions. We report here effective interactions between photons created using a quantum dot weakly coupled to a cavity. We show that a passive single-photon non-linearity can modify the counting statistics of a Poissonian beam, sorting the photons in number. This is used to create strong correlations between detection events and sort polarisation correlated photons from an uncorrelated stream using a single spin. These results pave the way for optical switches operated by single quanta of light.