Coulomb drag between ballistic quantum wires

TL;DR

This paper develops a kinetic theory for Coulomb drag in ballistic 1D electron systems, highlighting the importance of equilibration processes and showing how they influence the temperature dependence and interaction strength effects on drag resistivity.

Contribution

It provides a novel kinetic equation framework demonstrating the critical role of equilibration processes and their impact on Coulomb drag behavior in one-dimensional quantum wires.

Findings

Equilibration between right- and left-moving electrons is crucial for dc drag.

Forward scattering near the Fermi surface alone does not produce nonzero dc drag.

Slow equilibration leads to activation-like temperature dependence of drag resistivity.

Abstract

We develop a kinetic equation description of Coulomb drag between ballistic one-dimensional electron systems, which enables us to demonstrate that equilibration processes between right- and left-moving electrons are crucially important for establishing dc drag. In one-dimensional geometry, this type of equilibration requires either backscattering near the Fermi level or scattering with small momentum transfer near the bottom of the electron spectrum. Importantly, pairwise forward scattering in the vicinity of the Fermi surface alone is not sufficient to produce a nonzero dc drag resistivity $\rho_{\rm D}$, in contrast to a number of works that have studied Coulomb drag due to this mechanism of scattering before. We show that slow equilibration between two subsystems of electrons of opposite chirality, "bottlenecked" by inelastic collisions involving cold electrons near the bottom of the conduction band, leads to a strong suppression of Coulomb drag, which results in an activation dependence of $\rho_{\rm D}$ on temperature---instead of the conventional power law. We demonstrate the emergence of a drag regime in which $\rho_{\rm D}$ does not depend on the strength of interwire interactions, while depending strongly on the strength of interactions inside the wires.