Emission Quenching of Magnetic Dipole Transitions near a Metal Nanoparticle

The emission quenching of magnetic dipole transitions due to electromagnetic coupling to a metal nanoparticle is studied theoretically. We show that, at nanometer distances to the nanoparticle surface, the quenching is much weaker than that of electric dipole transitions, resulting in far higher radiative quantum efficiencies. This difference is explained by the fact that the electric field induced by an oscillating magnetic dipole and responsible for the energy transfer to the metal has a weaker distance dependence than the electric field of an electric dipole. Our results imply that magnetic dipole transitions may be superior to electric ones if coupling to a metallic nanoantenna over sub-10 nm distances is used to enhance optical emission from a quantum emitter.