Room temperature photon statistics of hexagonal boron nitride quantum emitters

Single photon sources are elementary building blocks for photonic quantum technologies. The recent discovery of quantum light emission from color centers defects in hexagonal boron nitride (hBN), has introduced a promising candidate for a room temperature single photon sourcl. However, a number of properties that determine the emission characteristics of these centers are not well understood.
In this work, we investigate the spectral and intensity fluctuations of emission from hBN color centers triggered by laser pulses. By tagging every photon count, we measure the Mandel parameter (Q) over several orders of magnitude of observation time scale. We report transformation of sub-Poissonian statistics of intensity fluctuations observed over the shorter (tens of nanosecond) times to super-Poissonian over the longer (tens of microseconds) times. We quantify the probability of two-photons events for hBN color centers and compare it to a reference Poissonian and quasi-thermal source of same average power. We compare the experimental results with those from light-emitter interaction model calculations. Our results may shine light on some of the open questions about hBN color centers, from their origins to their photophysical properties.