Polarization-correlated photon pairs from charged biexciton in a single GaAs quantum dot

We have studied micro-photoluminescence spectra of self-assembled single GaAs/AlGaAs quantum dots (QDs). Under non-resonant optical excitation, a single GaAs QD exhibits several sharp peaks in the PL spectra whose origins are the recombination of neutral or charged multi-excitonic complexes. In single photon correlation measurements, photons emitted from charged biexcitons and charged excitons show bunching which indicates that photon pairs are generated from the cascade recombination of the charged biexcitons. The result of polarization correlation measurements shows that each photon of the pairs is polarized linearly and orthogonally. These polarization features can be understood by the superposition of elliptically polarized photons affected by the electron–hole exchange interaction in the anisotropic QD.