  Converting signals between different electromagnetic modes is an asset for
future information technologies. In general, slightly asymmetric optical
nanoantennas enable the coupling between bright and dark modes sustained by an
optical nanoantenna. However, the conversion efficiency might be very low.
Here, we show that the additional incorporation of a quantum emitter allows to
tremendously enhance this efficiency. The enhanced local density of states
cycles the quantum emitter between its upper and lower level at an extremely
hight rate; hence converting the energy very efficient. The process is robust
with respect to possible experimental tolerances and adds a new ingredient to
be exploited while studying and applying coupling phenomena in optical
nanosystems.
