MERCREDI 27 JANVIER 2010 15 heures (Attention horaire inhabituel!) Salle Séminaire 5 Centre de Physique Théorique Marseille-Luminy Séminaire d'Intérêt Général Thierry Martin CPT Titre: Réponse en fréquence d'un condensateur mesoscopique en présence d'interactions fortes Résumé: We consider a one dimensional mesoscopic capacitor in the presence of strong electron interactions and compute its admittance in order to probe the universal nature of the relaxation resistance. We use a combination of perturbation theory, renormalization group arguments, and quantum Monte Carlo calculation to treat the whole parameter range of dot lead coupling. The relaxation resistance is universal even in the presence of strong Coulomb blockade when the interactions in the wire are sufficiently weak. We predict and observe a quantum phase transition to an incoherent regime for a Luttinger parameter K<1/2. Results could be tested using a quantum dot coupled to an edge state in the fractional quantum Hall effect.