  We report photon correlation measurements that allow us to observe unique
signatures of biexcitons in a single self-assembled InAs quantum dot. Photon
correlation measurements of biexciton emission exhibit both bunching and
antibunching under continuous-wave excitation while only antibunching is
observed under pulsed excitation. Cross-correlation between biexciton and
single-exciton peaks reveal highly asymmetric features, demonstrating that
biexciton and exciton emissions have strong correlations due to cascaded
emission. The anticipated correlation between the polarization of exciton and
biexciton emissions however, is absent under our excitation conditions. Photon
correlation measurements also provide evidence for the identification of the
charged exciton emission.
