Abstract

The negatively charged nitrogen-vacancy (NV) color center in diamond has been widely investigated for applications spanning from quantum information processing to nanoscale sensing [1] . Central to its utility is its combination of a long-lived electronic spin state with optical initialization and readout. However, the fidelity of room-temperature NV spin readout is limited, due to the low rate of detected spin-correlated fluorescence photons [2]. Plasmonic nanostructures are a natural fit for increasing the detected fluorescence rate as they can offer directional emission simultaneously with high Purcell enhancement across the broad NV spectrum [3], which has not been demonstrated in NV-coupled dielectric nanostructures [4]. In this work, we optimize and fabricate embedded plasmonic nanoantennas (Figure 1a) consisting of a diamond ridge capped and surrounded by silver with an internal silver bowtie. This design achieves high electric field intensity in the central gap (Figure 1b) as well as high directivity (Figure 1c), and as a result produces a high Purcell factor - collection efficiency product across a large spectral band (Figure 1d). The resulting embedded nanoantennas (Figures 1e,1f) have a simulated far-field detected photon rate figure of merit of 17.5 integrated across the NV spectrum. This improves upon the state-of-the-art [3] by an order of magnitude, and represents a step towards single-shot NV electron spin readout at room temperature.

© 2017 IEEE