Noise Correlations in a Coulomb Blockaded Quantum Dot

TL;DR

This study measures current noise correlations in a tunable Coulomb blockaded quantum dot, revealing how auto- and cross-correlations evolve with bias and tunneling conditions, providing insights into quantum transport mechanisms.

Contribution

It presents the first detailed measurement of auto- and cross-correlations in a Coulomb blockaded quantum dot with multiple leads, highlighting their dependence on bias and tunneling regimes.

Findings

Auto-correlation shifts from super- to sub-Poissonian as bias increases.

Cross-correlation changes from positive to negative with bias in three-lead configuration.

Cross-correlations are proportional to excess noise in weak tunneling limit.

Abstract

We report measurements of current noise auto- and cross-correlation in a tunable quantum dot with two or three leads. As the Coulomb blockade is lifted at finite source-drain bias, the auto-correlation evolves from super-Poissonian to sub-Poissonian in the two-lead case, and the cross-correlation evolves from positive to negative in the three-lead case, consistent with transport through multiple levels. Cross-correlations in the three-lead dot are found to be proportional to the noise in excess of the Poissonian value in the limit of weak output tunneling.