Polyharmonic surface acoustic wave control of single-electron transport in semimetallic carbon nanotubes

We have investigated theoretically the possibility of improving the accuracy of single-electron charge pumping in semimetallic carbon nanotubes by using a polyharmonic surface acoustic wave modulation. The Pareto-optimal parameters were numerically obtained for the modulation with up to three harmonics, based on the assumption that the accuracy of the charge pumping is determined by two factors: the minigap and the valley isolation of the miniband structure created by the modulation. It is shown that the accuracy can be improved by modulation using two or three harmonics rather than a single-frequency acoustic wave. This is because the trade-off between the above two factors can be decreased in the presence of higher harmonics.