VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013


 Nanophysics: from fundamentals to applications

(the return)


Tuesday 6

› 8:30 - 9:00 (30min)
Dissipation and supercurrent fluctuations in a diffusive NS ring
Helene Bouchiat  1@  , Bastien Dassonneville  1@  , Meydi Ferrier  1@  , Sophie Gueron  1@  
1 : Laboratoire de Physique des Solides  (LPS)  -  Website
CNRS : UMR8502
Université Paris-Sud, Laboratoire de Physique des Solides 91405 Orsay -  France

A mesoscopic hybrid Normal/ Superconducting (NS) ring is characterized by a dense Andreev spectrum with a flux dependent minigap. We measure the linear response to a high frequency flux, in a wide frequency range, with a multimode superconducting resonator. We find that the current response contains, beside the well known dissipation-less Josephson contribution, a large dissipative component. At high frequency compared to the minigap and low temperature we find that the dissipation is due to transitions above the minigap. In contrast, at lower frequency there is range of temperature for which dissipation is caused predominantly by the relaxation of the Andreev states' population.
This dissipative response, related via the fluctuation dissipation theorem to a non intuitive zero frequency thermal noise of supercurrent, is characterized by a phase dependence dominated by its second harmonic, as predicted long ago , but never yet observed before.

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