CPM Seminar

Experimental Quantum Electronics in 10-nm Scale Carbon System

Alexandre Champagne

Concordia University

The possibility to make 10-nm-scale, and low-disorder, suspended graphene and SWCNT devices would open up many possibilities to study and make use of strongly coupled quantum electronics and quantum mechanics. We first present a versatile method, based on the electromigration of gold-on-carbon bow-tie bridges, to fabricate low-disorder suspended graphene and SWCNT ballistic transistors and quantum dots with lengths ranging from 6 nm up to 100 nm. We can controllably tear the width of suspended graphene channels from over 100 nm down to 27 nm and create high-quality suspended quantum dots. In wider graphene devices, we explore the ballistic transport of Dirac fermions and demonstrate few-nm scale p-n junctions.

In suspended ultra-short SWCNTs, we show a giant, and tunable, electron-hole asymmetry in charge transport. For instance, the same device can behave either a ballistic conductor or a quantum dot depending on the type of charge carriers (gate controlled). We demonstrate that SWCNTs make ultra-high (100 GHz) frequency NEMS systems where we observe simultaneously strong electron-electron interactions (Kondo) and strong electron-vibron coupling. We briefly conclude with our ongoing effort to explore the strain-engineering of these quantum NEMS.