The development of practical optical quantum technologies requires the reproducible and scalable production of single quantum emitters with long optical coherence times that can be readily integrated with devices[1]. Here, we demonstrate the superior optical properties of chemically-made, colloidal lead halide perovskite quantum dots (PQDs)(Fig.A) as single emitters. Using photon-correlation Fourier spectroscopy at low temperatures, we find that PQDs exhibit long optical coherence times and small exciton fine-structure splittings (Fig. B, C)[3]. The long coherence and short radiative emission lifetimes (210 ps) renders the PQD emission linewidth near the Fourier transform limit. Moreover, we show that spectral diffusion is drastically reduced compared to other colloidal quantum dots and that the majority (50-80%) of photons is emitted coherently. The fraction of coherent photons is already comparable to silicon vacancy centers in diamond as often-used emitters in quantum photonics. We further take steps towards improving the low-temperature stability and reducing inhomogeneity with the synthesis. Our results suggest that, while all other colloidal quantum dot materials suffer from prohibitively incoherent emission, PQDs can be explored as sources of indistinguishable single photons that can be processed from solution onto virtually any substrate and easily coupled with hybrid nano-photonic components like waveguides or plasmonic gap cavities. The talk concludes with our efforts to integrate PQDs into 2D-heterostructure devices capable of emitting single photons of electrically-tunable color, a first step towards the realization of PQD-based quantum light sources.

Colloidal perovskite quantum dots as scalable emitters of coherent single photons

2019 Fall National Meeting

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