laboratoire pierre aigrain
électronique et photonique quantiques
laboratoire pierre aigrain

Hybrid Quantum Circuits

Cavity QED with mesoscopic circuits

Cavity QED with strongly correlated systems

An atom coupled to a harmonic oscillator is one of the most illuminating paradigms for quantum measurements and amplification. Recently, the joint development of artificial two-level systems and high finesse microwave resonators in superconducting circuits has brought the realization of this model on-chip. This “circuit Quantum Electro-Dynamics” architecture allows, at least in principle, to combine circuits with an arbitrary complexity. In this context, quantum dots can also be used as artificial atoms. Importantly, these systems often exhibit many-body features if coupled strongly to Fermi seas, as epitomized by the Kondo effect. Combining such quantum dots with microwave cavities would therefore enable the study of a new type of coupled fermionic-photonic systems. In this work, the HQC team has demonstrated such an architecture. We couple a quantum dot in the Kondo regime to a single mode of the electromagnetic field and take a step further towards circuit QED experiments with a many body system.

Spin quantum bits with ferromagnetic contacts : strong spin/photon coupling

The multi-terminal nano-spin-valve demonstrates a new type of coupling of the spin and the orbital motion of electrons in confined geometries. In collaboration with Audrey Cottet of the theory group of LPA, the HQC team has proposed to use such an “artificial spin-orbit coupling” for a new spin quantum bit proposal [1]. The combination of interface exchange effects with a double quantum dot setup is predicted to enable the strong coupling between a single electronic spin and cavity photons, a key ingredient for using the methods of cavity QED for manipulating quantum states.