Detection of non-Gaussian Fluctuations in a Quantum Point Contact

TL;DR

This paper reports an experimental investigation of current fluctuations in a quantum point contact, measuring the full counting statistics and confirming non-Gaussian behavior predicted by quantum transport theory.

Contribution

The study introduces a precise measurement technique for the first three cumulants of transmitted charge in a quantum point contact, accounting for external circuit effects.

Findings

Third cumulant matches non-Poissonian theoretical predictions

External circuit effects are effectively corrected in measurements

Demonstrates non-Gaussian fluctuation behavior in quantum transport

Abstract

An experimental study of current fluctuations through a tunable transmission barrier, a quantum point contact, are reported. We measure the probability distribution function of transmitted charge with precision sufficient to extract the first three cumulants. To obtain the intrinsic quantities, corresponding to voltage-biased barrier, we employ a procedure that accounts for the response of the external circuit and the amplifier. The third cumulant, obtained with a high precision, is found to agree with the prediction for the statistics of transport in the non-Poissonian regime.