Dependence of the Macroscopic Quantum Tunneling Rate on Josephson Junction Area

/Nb Josephson junctions (JJs) of different areas. Employing on-chip lumped element inductors,we have decoupled the JJs from their environmental line impedances at the frequencies relevant forMQT. This allowed us to study the crossover from the thermal to the quantum regime in the lowdamping limit. A clear reduction of the crossover temperature with increasing JJ size is observedand found to be in excellent agreement with theory. All junctions were realized on the same chipand were thoroughly characterized before the quantum measurements.