Mesoscopic physics

The team’s activities cover various aspects of dynamical quantum transport, from electronic quantum optics and cavity quantum electrodynamics to Dirac fermion electronics, topological matter and microwave quantum photonics. It studies model systems such as carbon nanotubes, graphene, quantum Hall effect edge channels in semiconductor heterostructures, or topological insulators. The devices are mostly fabricated in the laboratory using cleanroom nanofabrication techniques. They are characterized by quantum transport and noise measurements in the microwave range. The team’s four major themes are described below.

Dynamical transport in graphene

Our team studies electronic dynamics in graphene/BN heterostructures of high mobility by transport and microwave experiments. We are interested in interaction effects of Dirac fermions in optic electronics and plasmonic regimes, as well as in coupling to light and phonon-polaritons in van der Waals insulators. Beyond graphene, this approach is applied to semiconducting and topological insulator heterostructures.

Electronic quantum optics

Our team studies two-dimensional layers of high-mobility electrons (AsAlGa/AsGa). On one hand, the dynamics of coherent conductors: how are quantum Kirchhoff laws modified at high frequency? What is the relaxation time of quantum coherent RC circuit? What is the elementary quantum inductance associated to a quantum mode? On the other hand, manipulation of single electrons: as analogy with quantum optics, can we realize a coherent single electron source, realize the entanglement of two electrons and use it as flying qubits?

Anyon fractional statistics in mesoscopic colliders

Our team investigates the fractional statistics of anyons using the geometry of anyon colliders, where two dilute beams of anyons are generated at the input of an anyon beam splitter. We have focused so far on abelian anyons, for which the accumulated phase associated to the exchange of two particles can take arbitrary values between 0 (bosonic case) and π (fermionic case). We use high mobility GaAs/AlGaAs heterostructures under a strong magnetic field to reach the fractional quantum Hall effect whose elementary excitations are anyons. By sending anyon excitations towards a beam-splitter and by measuring the correlations between the output electrical currents, we can probe the tendency of anyons to bunch together at the splitter output, which provides information on their fractional statistics.

Interferometer in a Hall effect resonator

Resonators and radiofrequency interferometry in the quantum Hall effect

Our team studies two-dimensional high-mobility electron gas (AsAlGa/AsGa) in order to realize magneto-plasmonic resonators in quantum Hall effect structures. The study of these resonators allow us to better understand the properties of the quantum Hall effect (integer and fractional) by studying the microwave absorption. One of the interests of this type of system is the possibility to build interferometers that could allow us to probe the statistical properties of fractional quasiparticles and, in particular, evidence their theorized non-abelian anyonic statistic.

Quantum skyrmionics

Our team theoretically studies the quantum and nonequilibrium skyrmion dynamics with a focus on developing strategies for bringing a novel macroscopic qubit design based on magnetic skyrmions to fruition. In particular, we aim to understand the microscopic mechanisms that create noise, design schemes to control sources of decoherence built upon spectral engineering, study the coherent interaction of skyrmion qubits with other quantum modules, and achieve long-distance tunable qubit coupling.