Direct evidence of macroscopic quantum effects at high temperature

We present experiments; on macroscopic quantum effects in Josephson junctio ns with different relevant junction parameters at a temperature well above the classical-quantum crossover temperature. This has been possible by exte nding the measurements on the escape rate out of the metastable state at hi gher sweeping frequency (dI/dt up to 100 A/sec.) in order to induce non-sta tionary conditions in the energy potential describing the junction dynamics . The non-stationary regime for the system allows a direct observation of e nergy level quantitation when the rate of change of the external energy, me asured in terms of the level spacing, is fast with respect to the thermal t ransitions between levels.