SINUSOIDAL GATE VOLTAGES FOR A 3-GATE SINGLE-ELECTRON PUMP

The characteristics of a three-gate single electron pump with four sma ll tunnel junctions have been studied by simple calculations. Comparin g the charging energy of a three-gate pump for different configuration s of excess electrons, we obtained the equilibrium energy planes in a three dimensional (3D) gate-voltage space. The polygon formed by the u nion of the equilibrium energy planes fog all configurations nearest t o a given configuration is depicted in the 3D space. Inside the polygo n, the configuration of excess electrons is stable. The pump can be op erated by applying a set of sinusoidally varying gate voltages, whose trajector in the 3D space is presented.