Quantized acoustoelectric single electron transport close to equilibrium

Single electron transport driven by surface acoustic waves (SAWs) is studied in the low power regime. The measurements are performed on a one-dimensional (1D) channel in a GaAs∕AlGaAs split-gate structure that is not dominated by unintentional impurities. The effective electric amplitude of the SAW is calibrated with the 1D subband energy splitting of the channel. Using this calibration, a close-to-equilibrium transport regime is identified, in which the SAW amplitude is on the order of the 1D subband energy splitting. In a proof of principle experiment, a quantized current I=1ef (f, frequency of the SAW; e, elementary charge) is generated close to equilibrium. Compared to the extensively studied nonequilibrium regime at high acoustic powers, heating is reduced close to equilibrium. This may improve the precision of quantum current standards based on SAW driven single electron transport.