Andreev-Coulomb Drag in Coupled Quantum Dots

TL;DR

This paper demonstrates that replacing a normal electrode with a superconductor in coupled quantum dots significantly enhances Coulomb drag via Andreev processes, which can be controlled and distinguished from single-particle effects.

Contribution

It introduces a method to boost Coulomb drag in quantum dots using superconducting electrodes and identifies Andreev processes as the dominant mechanism at low temperatures.

Findings

Coulomb drag is enhanced with superconducting electrodes.

Andreev processes dominate at low temperatures and strong coupling.

Drag current sign inversion distinguishes mechanisms.

Abstract

The Coulomb drag effect has been observed as a tiny current induced by both electron-hole asymmetry and interactions in normal coupled quantum dot devices. In the present work we show that the effect can be boosted by replacing one of the normal electrodes by a superconducting one. Moreover, we show that at low temperatures and for sufficiently strong coupling to the superconducting lead, the Coulomb drag is dominated by Andreev processes, is robust against details of the system parameters and can be controlled with a single gate voltage. This mechanism can be distinguished from single-particle contributions by a sign inversion of the drag current.