Resonance fluorescence and indistinguishable photons from a coherently driven B centre in hBN

TL;DR

This study demonstrates resonant excitation and high-coherence photon emission from B centres in hBN, showcasing their potential for integrated quantum photonics through advanced optical rejection techniques.

Contribution

The paper introduces a hybrid structure enabling resonant excitation of B centres in hBN, achieving high coherence and two-photon interference, advancing quantum photonics applications.

Findings

Resonant excitation of B centres in hBN achieved.

High two-photon interference visibility (~0.92).

Observation of optical coherence signatures like Mollow triplet and Hong-Ou-Mandel interference.

Abstract

Optically active defects in hexagonal boron nitride (hBN) have become amongst the most attractive single-photon emitters in the solid state, owing to their high-quality photophysical properties, combined with the unlimited possibilities of integration offered by the host two-dimensional material. In particular, the B centres, with their narrow linewidth, low wavelength spread and controllable positioning, have raised a particular interest for integrated quantum photonics. However, to date, either their excitation or their detection has been performed non-resonantly due to the difficulty of rejecting the backreflected laser light at the same wavelength, thereby preventing to take full benefit from their high coherence in quantum protocols. Here, we make use of a narrow-linewidth emitter integrated in a hybrid metal-dielectric structure to implement crossed-polarisation laser rejection. This allows us to observe resonantly scattered photons, with associated experimental signatures of optical coherence in both continuous-wave (cw) and pulsed regimes, respectively the Mollow triplet and Hong-Ou-Mandel interference from zero-phonon-line emission. The measured two-photon interference visibility of 0.93 +/- 0.21 and 0.92 +/- 0.26 we measured for two emitters demonstrate the potential of B centres in hBN for applications to integrated quantum information.