  We show that small numbers of electrons, including a single electron, can be
held in a novel electrostatic trap above the surface of superfluid helium. A
potential well is created using microfabricated electrodes in a 5 micron
diameter pool of helium. Electrons are injected into the trap from an electron
reservoir on a helium microchannel. They are individually detected using a
superconducting single-electron transistor (SET) as an electrometer. A Coulomb
staircase is observed as electrons leave the trap one-by-one until the trap is
empty. A design for a scalable quantum information processor using arrays of
electron traps is presented
