We demonstrate triggered single photon emission at room temperature from a site-controlled III-nitride quantum dot embedded in a nanowire. Moreover, we reveal a remarkable temperature insensitivity of the single photon statistics, and a g((2))[0] value at 300 K of just 0.13. The combination of using high-quality, small, site-controlled quantum dots with a wide-bandgap material system is crucial for providing both sufficient exciton confinement and an emission spectrum with minimal contamination in order to enable room temperature operation. Arrays of such single photon emitters will be useful for room-temperature quantum information processing applications such as on-chip quantum communication.

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Wide bandgap III-nitride quantum dots (QDs) are promising materials for the realization of solid-state single-photon sources, especially operating at room temperature. However, so far a large degree of inhomogeneous broadening induced by spectral diffusion has compromised their use. Here, we demonstrate the ultraclean emission from single GaN QDs formed at macrostep edges in a GaN/AlGaN quantum well. As a likely consequence of the high growth temperature and hence a reduced defect density, spectral diffusion is heavily suppressed to levels at least 1 order of magnitude lower than conventional GaN QDs. A record narrow line width of as small as 87 μeV is obtained, while the low inhomogeneous broadening enables us to assess an upper limit of homogeneous broadening in the QDs (27 μeV). Furthermore, the uncontaminated emission facilitates the generation of ultraviolet single-photons with unprecedented purity (g(0) = 0.02). The realization of high-quality GaN QDs will enable exploration of optoelectronic properties of III-nitrides, opening up the possibility of realizing single-photon quantum information systems operating at room temperature.

Sources of single photons are of central importance for the realization of several quantum information technologies including teleportation, cryptography, true random number generation, metrology, and some varieties of quantum computing. In principle the generation of single photons can be achieved via an optical transition in a quantum two-level system sufficiently separated from its environment. Solid-state semiconductor quantum dots are convenient structures that can provide such two-level systems, with engineered and tunable transition energies, but cryogenic temperatures are required in the vast majority of experiments in order to facilitate both carrier confinement and spectral isolation. The large-scale on-chip integration of such devices, however, due to inherent system heating, will require individual elements that can operate at temperatures in excess of room temperature. Here we report single-photon emission from an isolated state in a position-controlled GaN nanowire quantum dot at an unprecedented ambient temperature of 350 K (170 °F, 77 °C).

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