# Coulomb drag of excitons in Bose-Fermi mixtures

## TL;DR

This paper develops a microscopic theory of Coulomb drag in a hybrid system of electrons and dipolar excitons, analyzing how interactions and temperature affect cross-mobility in different exciton phases.

## Contribution

It introduces a detailed theoretical framework for Coulomb drag in electron-exciton systems, considering both normal and condensate phases and their temperature and separation dependencies.

## Key findings

- Screening causes exponential damping of cross-mobility at low temperatures in the normal phase.
- Exciton interactions lead to robust bosonic transport via Bogoliubov quasiparticles at low temperatures.
- Temperature and interlayer separation significantly influence the Coulomb drag effect.

## Abstract

We develop a microscopic theory of the Coulomb drag effect in a hybrid system consisting of spatially separated two-dimensional quantum gases of degenerate electrons and dipolar excitons. We consider both the normal-phase and condensate regimes of the exciton subsystem and investigate the cross-mobility of the system being the kinetic coefficient, which couples the static electric field applied to the electron layer with the particle density current (flux) in the exciton subsystem. We study the temperature dependence of the cross-mobility and its dependence on the interlayer separation. We show that exciton-exciton interaction plays a dramatic role. If the exciton gas is in the normal phase, then the screening of interlayer interaction by the exciton subsystem results in an exponential damping of the cross-mobility with the decrease of temperature, while at low temperatures, the interactions result in a robust bosonic transport due to the emergence of the Bogoliubov quasiparticles.