Fig. 1

Single photon emission from hBN. a Two-dimensional hBN hosting a fluorescent defect. b Photoluminescence spectrum of the single defect in hBN under 675 nm excitation. c Second-order autocorrelation measurement g⁽²⁾(τ) of the defect with a dip at g⁽²⁾(0) ≈ 0.25, indicating single photon emission. d Saturation curve of the emitter under excitation with a 708 nm laser. The solid line is the fit to \(I = I_\infty \times P/(P + P_{{\mathrm{sat}}})\), according to which the 50% of the saturated emission occurs at 14 mW. Inset: emission polarization curve of the emitter. The emission dipole is in the plane of the layered host crystal. (Note: the 708 nm laser was used in lieu of the 675 nm one for measurements requiring high power). e Photoluminescence spectra of the single defect under three excitation conditions: low-power (10 µW) 532 nm laser (green trace), high-power 675 nm laser (purple trace) and coincident excitation with both lasers (red trace). It is noteworthy that the spectrum under excitation with the 532 nm laser (green trace) has been multiplied tenfold for display purposes. f Nonlinear increase of the emitter brightness upon a linear increase in the power of the 532 nm excitation laser coincident with the 675 nm excitation laser. Scale bar is 500 nm