Trapping a single electron on helium using a superconducting resonator

Electrons on helium is a unique 2-dimensional system on the interface of superfluid helium and vacuum. The motional and spin states of a single electron trapped on superfluid helium could form an ultra-stable building block of a novel hybrid quantum computer. To trap a single electron on helium, a small electrostatic trap at the tip of a superconducting microwave resonator can serve as a quantum dot. For the first time, we demonstrate electron loading and unloading of such a quantum dot, which is detected through resonance frequency shifts. By repeatedly partially unloading the dot, we show resonant signatures of three, two and one electron(s). Additionally, we discuss properties of the single electron trap and figures of merit for an electron-on-helium qubit.