Dynamics of a pulsed single photon source

We propose and demonstrate a method for an independent verification of a degree of single photon purity and coherence applicable for all single-photon emitters used in pulsed mode. Using two-time second-order correlation measurements, we reconstruct the dynamics of the nonclassical photon wavepacket. This reveals the temporal evolution of the photon field during the excitation-relaxation cycle of an emitter. The technique allows for the simultaneous measurement of multiphoton content and decoherence. Here we applied this technique to characterize a nonclassical state produced from a single InAs quantum dot (QD). We experimentally observe variations in the degree of multiphoton content and coherence of the wavepacket. A rate equation is introduced to explain multiphoton variations of our source and is found to describe the observed two-dimensional second-order correlation function accurately.