Quantum computing with electrons floating on liquid helium

A quasi-two-dimensionaI set of electrons (1 < N < 10(9)) in vacuum, trapped in one-dimensional hydrogenic Levels above a micrometer-thick film of liqu id helium, is proposed as an easily manipulated strongly interacting set of quantum bits. Individual electrons are laterally confined by micrometer-si zed metal pads below the helium. Information is stored in the lowest hydrog enic levels. With electric fields, at temperatures of 10(-2) kelvin, change s in the wave function can be made in nanoseconds. Wave function coherence times are 0.1 millisecond. The wave function is read out with an inverted d c voltage, which releases excited electrons from the surface.