Supercurrent decay of Josephson junctions in non-stationary conditions: experimental evidence of macroscopic quantum effects

We present data on the rate of escape from the supercurrent state of Josephson junctions as function of the external energy in non-stationary conditions. We get experimental evidence of energy level quantization in a Josephson junction at high temperatures. For the first time, we present a direct measurement of the energy level width as a function of the level energy. (C) 2000 Published by Elsevier Science B.V. All rights reserved.