Controlling the polarisation correlation of photon pairs from a charge-tuneable quantum dot

TL;DR

This paper investigates how the charge state of a quantum dot affects the polarization correlation of photon pairs emitted during biexciton decay, with implications for entangled photon sources.

Contribution

It demonstrates control over polarization correlation via charge tuning in a quantum dot, highlighting the impact of charge states on photon entanglement quality.

Findings

Maximized neutral exciton emission improves biexciton decay efficiency

Correlation drops as negative charge state emission increases

Electronic spin-scattering likely causes reduced polarization correlation

Abstract

Correlation between the rectilinear polarisations of the photons emitted from the biexciton decay in a single quantum dot is investigated in a device which allows the charge-state of the dot to be controlled. Optimising emission from the neutral exciton states maximises the operating efficiency of the biexciton decay. This is important for single dot applications such as a triggered source of entangled photons. As the bias on the device is reduced correlation between the two photons is found to fall dramatically as emission from the negatively charged exciton becomes significant. Lifetime measurements demonstrate that electronic spin-scattering is the likely cause.