Doubly Resonant Nanoantennas on Diamond for Spatial Addressing of Spin States.

The negatively charged nitrogen-vacancy (NV) color center in diamond is an important atom-like system for emergent quantum technologies and sensing at room temperature. The light emission rates and collection efficiency are key issues toward realizing NV-based quantum devices. In that aspect, we propose and experimentally demonstrate a selective and spatially localized method for enhancing the light-matter interaction of shallow NV centers in bulk diamonds. This was achieved by polarized doubly resonant plasmonic antennas, tuned to the NV phonon sideband transition peak in the red and the narrowband near infrared (NIR) singlet transition. We obtained a photoluminescence (PL) enhancement factor of about 10 from NV centers within the hot spot of the antenna area (excluding the extraction efficiency enhancement) and similar emission lifetime reduction. The functionality of the double resonance antenna is controlled by the impinging light polarization.