Blocking transport resonances via Kondo entanglement in quantum dots

TL;DR

This paper investigates how Kondo entanglement in carbon nanotube quantum dots can suppress conduction channels, revealing new insights into many-body correlations and their impact on transport properties.

Contribution

It uncovers a novel aspect of Kondo correlations where entanglement blocks conduction channels, demonstrated through gate-tuned inelastic cotunneling lines in carbon nanotubes.

Findings

Inelastic cotunneling lines disappear when tuning gate voltage.

Only Kramers pseudospin flip resonances are observed below the Kondo scale.

Kondo entanglement can block conduction channels contrary to typical expectations.

Abstract

Many-body entanglement is at the heart of the Kondo effect, which has its hallmark in quantum dots as a zero-bias conductance peak at low temperatures. It signals the emergence of a conducting singlet state formed by a localized dot degree of freedom and conduction electrons. Carbon nanotubes offer the possibility to study the emergence of the Kondo entanglement by tuning many-body correlations with a gate voltage. Here we quantitatively show an undiscovered side of Kondo correlations, which counterintuitively tend to block conduction channels: inelastic cotunneling lines in the magnetospectrum of a carbon nanotube strikingly disappear when tuning the gate voltage. Considering the global \SUT\ $\otimes $ \SUT\ symmetry of a carbon nanotube coupled to leads, we find that only resonances involving flips of the Kramers pseudospins, associated to this symmetry, are observed at temperatures and voltages below the corresponding Kondo scale. Our results demonstrate the robust formation of entangled many-body states with no net pseudospin.