A system for measuring auto- and cross-correlation of current noise at low temperatures

TL;DR

This paper presents a two-channel noise measurement system operating at low temperatures, capable of accurately measuring current noise spectra and cross-correlations in electronic devices near 2 MHz, using cryogenic amplification and FFT techniques.

Contribution

It introduces a novel measurement setup combining cryogenic amplification and FFT-based spectral analysis for low-temperature current noise characterization.

Findings

Resolved full shot noise of 100 pA with 10 s integration

Demonstrated bias-dependent noise in GaAs/AlGaAs quantum point contact

Calibrated gain and temperature using Johnson noise thermometry

Abstract

We describe the construction and operation of a two-channel noise detection system for measuring power and cross spectral densities of current fluctuations near 2 MHz in electronic devices at low temperatures. The system employs cryogenic amplification and fast-Fourier-transform based spectral measurement. The gain and electron temperature are calibrated using Johnson noise thermometry. Full shot noise of 100 pA can be resolved with an integration time of 10 s. We report a demonstration measurement of bias-dependent current noise in a gate defined GaAs/AlGaAs quantum point contact.