Electrically tunable quantum emitters in an ultrathin graphene - hexagonal boron nitride van der Waals heterostructure

The recent discovery of solid-state single-photon emitters in two-dimensional host systems has unveiled a huge potential for quantum information processing and integrated nanophotonics.
In this context, hexagonal boron nitride (h-BN), owing to its unique optical properties, has emerged as a highly promising candidate for exploring atomic defect-related quantum emission. However, the presence of inhomogeneous energy distribution and spectral diffusion of the zero-phonon line (ZPL) makes it difficult to achieve the emission of indistinguishable photons as required for many applications. Stark effect-induced spectral tuning of the ZPL is able to compensate intrinsic local strain and electrostatic fields, which constitute the main sources of inhomogeneity and instability in the emission from individual h-BN defects.
Here, we investigate the Stark tuning of quantum emitters in few-layer h-BN sheets by means of low-temperature confocal photoluminescence spectroscopy. The required vertical electric field is implemented using a graphene top contact. The emitters can be effectively and reproducibly tuned, revealing a high robustness under repeated gate voltage sweep cycles. Moreover, we demonstrate an electric field-induced modulation of the emission intensity and fluorescence lifetime.