Single Quantum Dot Coupled to a Scanning Optical Antenna: A Tunable Superemitter

The interaction of a single quantum dot with a bowtie antenna is demonstrated for visible light. The antenna is generated at the apex of a ${\mathrm{Si}}_3{\mathrm{N}}_4$ atomic force microscopy tip by focused ion beam milling. When scanned over the quantum dot, its photoluminescence is enhanced while its excited-state lifetime is decreased. Our observations demonstrate that the relaxation channels of a single quantum emitter can be controlled by coupling to an efficiently radiating metallic nanoantenna.