Electrons bound to the surface of liquid helium has been proposed as a potential qubit. A qubit is a two state system that behaves quantum mechanically, and potentially would be the building block for a quantum computer. In the case of electrons on helium the electron is bound electrostatically to it's image charge reflected in an conductor below the liquid helium layer. The liquid helium acts as an impenetrable barrier and maintains the bound state.
One of the challenges with building a quantum computer is finding quantum two state systems that maintain their coherence long enough to do a calculation. Electrons on helium are expected to have very long coherence times because they are relatively isolated in their environment.
In this paper we show that by varying electrical potentials on a charge-coupled device (CCD)-like array, we can transfer individual electrons. This is a necessary step in creating quantum gates that will manipulate and entangle sets of electrons.

The top picture shows and electron and it's image charge separated by a layer of liquid helium. The bottom picture shows a schematic of our CCD device that can transport electrons.

Guillaume Sabouret, Forest R. Bradbury, Shyam Shankar, Julie A. Bert, and Stephen A. Lyon, Applied Physics Letters 92 082104 (2008). Full Text