Published on December 27 (2013) in Phys. Rev. X 3, 041034 (2013):
Supercurrent Spectroscopy of Andreev States
L. Bretheau, Ç. Girit, C. Urbina, D. Esteve, and H. Pothier
Detect single excitations in single channels caused by microwave excitation, through the related change in the supercurrent
see also previous publications on Josephson effect in weak links.