Dynamical Coulomb Blockade as a Local Probe for Quantum Transport

TL;DR

This paper demonstrates that dynamical Coulomb blockade (DCB) measured via STM can serve as a local probe to analyze quantum transport channels, revealing microscopic details and variations in atomic-scale contacts.

Contribution

It introduces DCB as a novel local measurement technique for quantum transport, supported by experimental results and ab initio calculations, advancing understanding of conduction channels.

Findings

DCB diminishes with increasing transmission in single-channel junctions, following the Fano factor.

Local differences in DCB correlate with changes in conduction channel configurations.

Experimental results align with theoretical predictions and ab initio calculations.

Abstract

Quantum fluctuations are imprinted with valuable information about transport processes. Experimental access to this information is possible, but challenging. We introduce the dynamical Coulomb blockade (DCB) as a local probe for fluctuations in a scanning tunneling microscope (STM) and show that it provides information about the conduction channels. In agreement with theoretical predictions, we find that the DCB disappears in a single-channel junction with increasing transmission following the Fano factor, analogous to what happens with shot noise. Furthermore we demonstrate local differences in the DCB expected from changes in the conduction channel configuration. Our experimental results are complemented by ab initio transport calculations that elucidate the microscopic nature of the conduction channels in our atomic-scale contacts. We conclude that probing the DCB by STM provides a technique complementary to shot noise measurements for locally resolving quantum transport characteristics.