Quantized pumped charge due to surface acoustic waves in a 1D channel

The adiabatic pumped current through an unbiased one dimensional (1D) channel, connected to two 1D leads and subject to surface acoustic waves (SAW), is calculated exactly for non-interacting electrons. For a broad range of the parameters, quantum interference generates a staircase structure of the time-averaged current, similar to experimental observations. This corresponds to integer values (in units of electronic charge) of the charge pumped during each period of the SAW. We also find staircases for higher harmonics. Quantum interference can thus replace Coulomb blockade in explaining the pumped charge quantization, particularly in the SAW experiments.