Quantum suppression of shot noise in atom-size metallic contacts

TL;DR

This paper demonstrates that in atom-sized gold contacts, conductance is mainly carried by nearly fully transmitted modes, with shot noise measurements providing clear evidence, unlike in aluminum contacts.

Contribution

It provides direct experimental evidence of mode transmission properties in atomic gold contacts using shot noise measurements, highlighting differences with aluminum.

Findings

Gold contacts are mainly transmitted by nearly fully open modes.

Single-atom gold contacts have minimal contribution from additional modes.

Aluminum contacts do not exhibit the same mode transmission characteristics.

Abstract

The transmission of conductance modes in atom-size gold contacts is investigated by simultaneously measuring conductance and shot noise. The results give unambiguous evidence that the current in the smallest gold contacts is mostly carried by nearly fully transmitted modes. In particular, for a single-atom contact the contribution of additional modes is only a few percent. In contrast, the trivalent metal aluminum does not show this property.