Direct measurement of the Josephson supercurrent in an ultrasmall Josephson junction.
We have measured the supercurrent flowing through a nonhysteretic, ultrasmall, voltage-biased Josephson junction. In contrast with experiments performed so far on hysteretic Josephson junctions, we find a supercurrent peak whose maximum I(s max) increases as the temperature T decreases. The asymptotic T = 0 value of I(s max) agrees with the junction Ambegaokar-Baratoff critical current, as predicted by theory.
Steinbach
A
A
Service de Physique de l'Etat Condensé, CEA-Saclay, F-91191 Gif-sur-Yvette, France.
Joyez
P
P
Cottet
A
A
Esteve
D
D
Devoret
M H
MH
Huber
M E
ME
Martinis
J M
JM