Generation of energy selective excitations in quantum Hall edge states

We operate an on-demand source of single electrons in high perpendicular magnetic fields up to 30 T, corresponding to a filling factor nu below 1/3. The device extracts and emits single charges at a tunable energy from and to a two-dimensional electron gas, brought into well defined integer and fractional quantum Hall (QH) states. We discuss ways to tune the emission energy as well as the sharpness of its distribution. We conclude that it can be used for sensitive electrical transport studies, e. g. of excitations and relaxation processes in QH edge states.