Adiabatic charge pump with a topological insulator nanowire device*

Quantised charge pumping has been proposed in several confined nanostructures. Although most realisations exploit the Coulomb blockade effect, a different mechanism based on the Landau-Büttiker formalism allows the implementation of adiabatic charge pumping in non-interacting electronic systems, exploiting the constructive interference of the scattering states. The presence of Dirac-like states, protected from non-magnetic disorder, at the surface of topological insulators (TI) can potentially lead to an improvement in the design of charge pump devices.

This work theoretically studies the implementation of quantised adiabatic charge pumping in a device based on a TI nanowire. In contrast to the two-dimensional platform counterpart, in TI nanowires the bulk transport is highly suppressed, making these nanostructures potentially useful for exploiting their protected surface states. We show how adiabatic charge pumping can be implemented in a recently proposed device where the charge confinement is achieved via a radius variation along the nanowire [1]. The pumping mechanism involves the use of only electrostatic gates and avoids the use of strong local magnetic fields, that are experimentally difficult to work with. Limitations and possible extensions of the protocol are also presented.

[1] R. Saxena et al, Phys. Rev. B 106, 035407 (2022).