Quantum Computing with Electrons Floating on Liquid Helium

We subbest using a 2D set (n ~ 10 sup 7/cm sup 2) of electrons in vacuum trapped in a set of 1D hydrogenic levels at a liquid helium interface, as an easily manipulated strongly interacting set of quantum (Q) bits. More precisely, we will show that at temperatures of 10 milliKelvin we can coherently change the wave function of one Q bit with modest 100 GHz microwave radiation in times of a few nanoseconds, provide an environment in which coherence times are 10 sup 5 times longer than this time; laterally confine these electrons using superconducting electrodes having 5 mu dimensions, show that coupling between pairs allows us to make single electron transitions which are strongly influenced by the quantum state of the neighbor; easily change the coupling with a voltage applied to a grid; and finally, read out the entire 2D array at some predetermined time using an inverted dc voltage pulse which initiates tunneling from the helium surface to an anode which could be, for example, a single electron area detection like a channel plate.