laboratoire pierre aigrain
électronique et photonique quantiques
 
laboratoire pierre aigrain
 

Seminaire, 3 décembre 2012

Cağlar Girit (CEA Saclay)
Detecting Excited Andreev Bound States in a One-Atom Contact

An abrupt variation of the superconducting phase—such as at a
superconducting tunnel junction or microbridge—results in the
creation of Andreev bound states. These states come in pairs with the
ground level giving rise to the conventional Josephson
current. Here we detect the transition to the excited Andreev bound
state in a superconducting atomic contact using a
Josephson junction as a broadband (5-100 GHz) spectrometer. Not only
do we clearly resolve the Andreev transition, but we
also identify spectroscopic lines arising from anticrossings with
electromagnetic modes of the environment. I will also present
the quantum theory describing the transitions and a complementary
detection technique using switching measurements.