Measurement of the Kondo cloud length via a quantum dot coupled to a 1d interferometer: Experiment (2/2)

The Kondo effect, known as the archetype of many-body correlations, arises from the interaction between a localized magnetic moment and surrounding conducting electrons. Advances of nanotechnology allow us to study the Kondo effect for a single magnetic impurity confined in a semiconductor quantum dot in contact with electron reservoirs. This development also makes it possible to embed a Kondo correlated state into an interferometer. However, the special extent of the Kondo cloud has yet to be measured.
In this work, we perform direct experimental measurement of the Kondo cloud length ξK by coupling a Kondo correlated quantum dot to ballistic, multi-channel quantum wires, one of which couples more strongly to the dot and works as a 1D Fabry–Perot (F-P) interferometer defined on a GaAs/AlGaAs heterostructure. We demonstrate that the measured Kondo temperature undergoes resonances with respect to the F-P fluctuations. By looking at the strength of the resonances versus the interferometer lengths, we are able to access the length of the Kondo cloud. We back up our results by comparing the behavior of the interferometer in the Kondo as well as the Coulomb Blockade Regimes.