Quantum charge pumping and electric polarization in Anderson insulators

TL;DR

This paper explores how adiabatic charge pumping occurs in strongly localized disordered one-dimensional systems, revealing a new mechanism involving multiple fluxes in parameter space that enhances charge transfer.

Contribution

It introduces a novel charge pumping mechanism in Anderson insulators based on multiple fluxes in parameter space, differing from traditional Thouless pumping.

Findings

Charge pumping occurs despite strong localization and no energy gap.

Multiple fluxes in parameter space enable efficient charge transfer.

The mechanism differs fundamentally from pure systems with a single flux.

Abstract

We investigate adiabatic charge pumping in disordered system in one dimension with open and closed boundary conditions. In contrast to the Thouless charge pumping, the system has no gap even though all the states are localized, i.e., strong localization. Charge pumping can be achieved by making a loop adiabatically in the two-dimensional parameter space of the Hamiltonian. It is because there are many $\delta$-function-like fluxes distributed over the parameter space with random strength, in sharp contrast to the single $\delta$-function in the pure case. This provides a new and more efficient way of charge pumping and polarization.