Screening, Nonadiabaticity, and Quantized Acoustoelectric Current

Quantized single-electron transport driven by surface acousticwaves (SAW) through a pinched-off narrow constriction isstudied theoretically. Long-range Coulomb interaction causesthe tunneling coupling between the two-dimensional electrongas (2DEG) and the moving minimum of the SAW-induced potentialto decay rapidly with time. The energy scale ℏ/τ,associated with the characteristic time of this decay τ,controls both the width of the transition regions between theplateaus and the slope of the plateaus. This sets a limit forthe accuracy of the quantization of acoustoelectric current atlow temperature.