VietNam 2013 

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

 QNplage

 Nanophysics: from fundamentals to applications

(the return)

 

Tuesday 6
Hybrid's

› 10:30 - 11:00 (30min)
Spectroscopy of Andreev bound states in an atomic contact
Cristian Urbina  1, *@  , Landry Bretheau  1@  , çağlar Girit  1@  , Daniel Esteve  1@  , Hugues Pothier  1@  
1 : Service de physique de l'état condensé  (SPEC)  -  Website
CEA, CNRS : URA2464
SPEC, CEA/Saclay Orme des Merisiers 91191 GIF SUR YVETTE CEDEX -  France
* : Corresponding author

The Josephson effect describes the flow of supercurrent in a weak link-such as a tunnel junction, nanowire or molecule-between two superconductors. It is the basis for a variety of circuits and devices. Microscopically, the supercurrent is carried by Andreev pair states, which are localized at the weak link. These states come in doublets and have energies inside the superconducting gap. Existing Josephson circuits are based on properties of just the ground state of each doublet, and so far the excited states have not been directly detected. Here we establish their existence through spectroscopic measurements of superconducting atomic contacts. The spectra, which depend on the atomic configuration and on the phase difference between the superconductors, are in complete agreement with theory. Our results show that in addition to the phase difference, each conduction channel of a Josephson weak link possesses an internal degree of freedom similar to a spin-1/2.


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