Embedded Files
Here are topics of current interest.
The tunnel time is an old and controversial problem from both theoretical and experimental points of view. The question is: “How long a particle takes to tunnel through a quantum barrier?” We demonstrate here that the photon emission results from the fluctuations of the current inside the tunneling barrier. Photon detection is then equivalent to a measurement of the current fluctuations at optical frequencies, allowing to probe the tunneling time. Based on this idea, we perform optical spectroscopy and electronic current fluctuation measurements in the far from equilibrium regime.
The study of current fluctuations can be done on conventional conductors such as avalanche diodes to understand complex electronic transport mechanisms [14] but also on quantum conductors to learn to control transport on the electron scale . This makes it possible to create quantum states of the electromagnetic field [10,7]. It is then necessary to place oneself at low temperatures and high frequencies in order to be able to neglect the thermal fluctuations compared to the quantum fluctuations linked to the quantification of the charge (shot noise). This limit is reached for temperatures of around ten mK and frequencies of the order of a few GHz.
This project explores the possibilities offered by circuit Quantum Electrodynamics to realize quantum fluids of light. By implementing arrays of coupled non-linear superconducting resonators, we will create artificial lattices for microwave photons in the presence of strong photon-photon interactions. Such circuits will simulate the Bose-Hubbard and the XY models with tunable parameters (hopping, interaction strength, ...) and arbitrary lattice geometries. The novelty of this project is to explore the out of equilibrium properties of these models both experimentally and theoretically. More precisely, we will revisit the physics of the superconducting to insulator transition in Josephson junction chains and the physics of the quantum Hall effect with microwave photons in arrays of cavities implementing an artificial gauge field.
The dynamics of quantum electronic transport have been studied for twenty years using high frequency measurements. The characteristic energies involved in these conductors at very low temperature (thermal energy kBT, charge energy Ec, superconducting gap) being of the order of ten μeV, the appropriate frequency domain is the microwave domain. This problem is the starting point of my research work. I became interested in the dynamics of elementary quantum circuits: the RC [11,16] and RL [17] circuits. This allowed me to highlight a time associated with the quantum dynamics of the electron which simply reflects the Heisenberg uncertainty principle: Ec/h. Still using broadband measurements, we are now interested in the study of the superconducting-insulating transition or the amplitude Higgs mode in a superconductors with a moving condensate [PRL 118,4 (2017)].
Page updated
Google Sites
Report abuse