Disclosed is a system and a method to use the system that includes a substrate to support a film of liquid helium and an electron subsystem confined by image forces in a direction perpendicular to the surface of the film, a side gate to electrostatically define a boundary of the electron subsystem, a trap gate to electrostatically define an electron trap located outside the boundary of the electron subsystem, and a load gate to selectively open and close access from the electron subsystem to the electron trap, wherein to open access to the electron trap is to apply a first load gate voltage to the load gate to allow the electrons to access the electron trap, and wherein to close access to the electron trap is to apply a second load gate voltage to the load gate to prevent the electrons from accessing the electron trap.