# Counterflow of electrons in two isolated quantum point contacts

## TL;DR

This paper investigates how a high bias in one quantum point contact induces a counterflow current in a nearby, isolated QPC, revealing phonon-mediated electron interactions that cause electrons to flow opposite to the drive current.

## Contribution

It demonstrates a novel counterflow effect between isolated QPCs driven by phonon interactions, expanding understanding of nonlocal electron dynamics in quantum nanostructures.

## Key findings

- Counterflow current flows opposite to drive current in the detector QPC.
- Maximum counterflow occurs when the detector QPC is at a conductance transition.
- Phonon-induced asymmetric electron excitation explains the counterflow phenomenon.

## Abstract

We study the interaction between two adjacent but electrically isolated quantum point contacts (QPCs). At high enough source-drain bias on one QPC, the drive QPC, we detect a finite electric current in the second, unbiased, detector QPC. The current generated at the detector QPC always flows in the opposite direction than the current of the drive QPC. The generated current is maximal, if the detector QPC is tuned to a transition region between its quantized conductance plateaus and the drive QPC is almost pinched-off. We interpret this counterflow phenomenon in terms of an asymmetric phonon-induced excitation of electrons in the leads of the detector QPC.