Tunable Kondo physics in a carbon nanotube double quantum dot

TL;DR

This study explores tunable Kondo effects in a carbon nanotube double quantum dot, demonstrating control over quantum states and phase transitions through magnetic fields, with results aligning with numerical models.

Contribution

It presents the first experimental realization of a tunable two-impurity Kondo system in a carbon nanotube device, enabling detailed study of quantum phase transitions.

Findings

Magnetic field tuning induces a crossover from local singlet to Kondo screened phase.

Experimental results agree with numerical renormalization group predictions.

System accesses the full range of charge regimes in a double quantum dot.

Abstract

We investigate a tunable two-impurity Kondo system in a strongly correlated carbon nanotube double quantum dot, accessing the full range of charge regimes. In the regime where both dots contain an unpaired electron, the system approaches the two-impurity Kondo model. At zero magnetic field the interdot coupling disrupts the Kondo physics and a local singlet state arises, but we are able to tune the crossover to a Kondo screened phase by application of a magnetic field. All results show good agreement with a numerical renormalization group study of the device.