Quantum dot circuits represent model systems for the study of
strong electronic correlations, epitomized by the Kondo effect. In
this thesis, we use light-matter interaction to study an
internal degree of freedom of such a many-body phenomenon. For
this purpose, carbon nanotube based quantum dot circuits
are embedded in a circuit quantum electrodynamics (cQED)
architecture. The coupling of a quantum dot to a high finesse
microwave cavity allows us to measure the compressibility of the
electron gas in the quantum dot with an unprecedented sensitivity.
Simultaneous measurements of the conductance and the
compressibility are performed and we observe that the Kondo
resonance in the conductance is transparent to microwave photons.
This reveals the predicted frozen charge dynamics in the quantum
dot, highlighting the separation of spin and charge degree of
freedom in this peculiar mechanism of electron transfer.
Quantum electronic circuits are also envisioned for
engineering Majorana fermions, a quasi-particle that obey
non-abelian statistics. I will present promising
preliminary results in the realization of a synthetic
spin-orbit coupling, a key ingredient for Majorana devices.