Non-classical light generated by a quantum dot: multi-color photons with tunable statistics

Abstract

We report the intensity and polarization correlations of two consecutively emitted photons from an optically excited single semiconductor quantum dot (SCQD). We show that a quantum dot is a source of non-classically correlated photons of various wavelengths, emitted due to the recombination of electron–hole (e–h) pairs from different collective many-carrier quantum states confined in the dot. We show that there are excitation power dependent intensity and polarization correlations among photons emitted at the same (“auto-correlations”), and at different wavelengths (“cross-correlations”). We observed a preferentially co-circularly-polarized cross-correlation at low excitation power, which is tentatively explained in terms of long electronic spin memory.