Towards Hybrid Quantum Information Processing with Electrons on Helium

Electrons above the surface of superfluid helium form a two-dimensional electron gas in which single-electron quantum dots can be defined using electrostatic gates submerged under the helium film. The quantized motion and spin state of such a trapped electron on helium can be coupled to a high finesse superconducting cavity in a hybrid circuit QED architecture [1]. The cavity is used for nondestructive readout and as a quantum bus mediating interactions between distant electrons or an electron and a superconducting qubit. Coupling between motional states and individual photons in the cavity is estimated at a Rabi frequency of $g/2\pi\sim 20$ MHz with coherence times exceeding 20 $\mu$s for charge and 1 s for spin [1, 2]. Here I will discuss recent experiments in which we successfully trap and detect a two-dimensional electron gas on helium in a dc-biased superconducting cavity. Experimental progress towards the single-electron regime will also be presented. \newline [1] D.I. Schuster, A.Fragner, M.I. Dykman, S. Lyon and R.J. Schoelkopf, Phys. Rev. Lett. 105, 040503 (2010) \newline [2] S. A. Lyon, Phys. Rev. A 74, 052338 (2006)