Adiabatic charge and spin transport in interacting quantum wires

TL;DR

This paper investigates how interactions in quantum wires influence charge and spin transport during adiabatic pumping, revealing conditions for quantization and the effects of finite size, temperature, and frequency.

Contribution

It establishes a relation between adiabatic charge/spin transport and backscattering conductances, highlighting the role of interactions and RG fixed points in quantization.

Findings

Quantized charge/spin transport occurs at RG stable fixed points.

Non-interacting electrons exhibit non-universal pumped charge.

Finite size, temperature, and frequency affect transport coefficients.

Abstract

We study charge and spin transport through an interacting quantum wire, caused by backscattering off an effective impurity potential with a periodic time-dependence. The adiabatic regime of this pump for charge and spin is shown to depend on the presence of interactions in the wire. Using symmetry and scaling properties of the quantum wire Hamiltonian we relate the charge $Q$ and spin $S$ transported through the wire in a period to an integral involving quasi-static backscattering conductances. We also show that the pumped charge $Q$ (or the spin $S$) is quantized in the adiabatic limit if the conductance of the system is zero at the stable fixed point of the renormalization-group (RG) transformations. By contrast, for a RG marginal conductance -- which is the case for non-interacting electrons -- the charge transported in a cycle is non-universal. Finite size, temperature, and frequency effects on the transported quantities follow from the relation between adiabatic transport coefficients (backscattering conductances) and the quasi-static conductance of the system.