Séminaire IQ: Benoît Douçot

Benoît Douçot Quantum dots coupled to several superconducting reservoirs The physics of quantum dots coupled to superconducting reservoirs offers a very interesting example of discrete energy levels with a tunable coupling to a macroscopic environment. Indeed, the sharp Andreev bound-states present in equilibrium are broadened at finite voltage bias into resonances as the result of multiple Andreev reflections (MAR). I will focuss on voltage configurations such that the resulting Hamiltonian is a periodic function of time. A specially interesting example is provided by a three terminal system biased at Va=-Vb and Vc=0. On top of the usual ac Josephson effect, dc quartet currents are expected, due to coherent processes involving two incoming Cooper from the c terminal recombining into one Cooper pair on terminal a and another one on terminal b. I will show how a simple physical picture, based on Floquet-Wannier-Stark ladders and semi-classical ideas, sheds light on this quartet physics. I will apply it also to discuss the onset of long-range correlations between two dots, mediated by non-local MAR processes.