Effects of dissipation and temperature on macroscopic quantum tunneling

Measurements of the tunneling rate " out of the zero-voltage state for several Nb edge junctions with differing shunt capacitances are described. At zero temperature, increasing the shunt capacitance lowers " in agreement with dissipative calculations of the macroscopic-quantum-tunneling rate. As temperature increases, ln["(T)"(0)]T2 as recently predicted. © 1985 The American Physical Society.