SQUIDs based set-up for probing current noise and correlations in three-terminal devices

TL;DR

This paper introduces a low-temperature experimental setup using SQUIDs for precise measurement of current noise and correlations in three-terminal devices, enabling detailed analysis of electronic fluctuations.

Contribution

The paper presents a novel SQUID-based setup for measuring current noise and correlations in three-terminal devices at millikelvin temperatures, with calibration and noise analysis.

Findings

Calibration confirms low intrinsic noise of the setup.

No intrinsic correlations detected due to measurement scheme.

Noise and correlations vary with applied DC current.

Abstract

We have implemented a new experimental set-up for precise measurements of current fluctuations in three-terminal devices. The system operates at very low temperatures (30 mK) and is equipped with three SQUIDs as low noise current amplifiers. A SQUID input coil is connected to each terminal of a sample allowing the acquisition of time-dependent current everywhere in the circuit. From these traces, we can measure the current mean value, the noise and cross-correlations between different branches of a device. In this paper we present calibration results of noise and cross-correlations obtained using low impedance macroscopic resistors. From these results we can extract the noise level of the set-up and show that there are no intrinsic correlations due to the measurement scheme. We also studied noise and correlations as a function of a DC current and estimated the electronic temperature of various macroscopic resistors.