Controlled dephasing of a quantum dot in the Kondo regime

TL;DR

This paper investigates how potential fluctuations in a nearby detector cause significant dephasing of Kondo-related coherent transport in a quantum dot, revealing that dephasing mainly affects the Kondo cloud in the leads.

Contribution

It demonstrates controlled dephasing of Kondo correlations in a quantum dot via potential fluctuations, highlighting the role of the Kondo cloud in dephasing mechanisms.

Findings

Dephasing suppresses coherent transport more strongly than expected.

Dephasing primarily affects the Kondo cloud, not the quantum dot itself.

Qualitative dephasing similar to Coulomb blockade regime observed.

Abstract

Kondo correlation in a spin polarized quantum dot (QD) results from the dynamical formation of a spin singlet between the dot's net spin and a Kondo cloud of electrons in the leads, leading to enhanced coherent transport through the QD. We demonstrate here significant dephasing of such transport by coupling the QD and its leads to potential fluctuations in a near by 'potential detector'. The qualitative dephasing is similar to that of a QD in the Coulomb Blockade regime in spite of the fact that the mechanism of transport is quite different. A much stronger than expected suppression of coherent transport is measured, suggesting that dephasing is induced mostly in the 'Kondo cloud' of electrons within the leads and not in the QD.