Nonlinear Transport in a Quantum Point Contact due to Soft Disorder Induced Coherent Mode Mixing

TL;DR

This paper demonstrates that soft disorder-induced coherent mode mixing in quantum point contacts causes nonlinear and asymmetric current responses, aligning well with recent experimental observations of conductivity nonlinearities.

Contribution

It reveals how soft impurity and boundary potentials induce nonlinear, asymmetric transport in QPCs through coherent mode mixing, a novel insight into disorder effects.

Findings

Coherent mode mixing leads to nonlinear current response.

The response is sensitive to voltage and gate voltage.

Results agree with recent experimental data.

Abstract

We show that the coherent mixing of different transverse modes, due to forward scattering of carriers by soft impurity- or boundary potentials leads to a nonlinear, asymmetric current response of quantum point contacts (QPC). The oscillating contribution to the current is sensitive both to driving voltage and to gate voltage in direct analogy to the electrostatic Aharonov-Bohm effect. Our calculations are in a good agreement with recent experimental data showing small-scale conductivity nonlinearities and asymmetry in QPC.