Observation of incoherent relaxation by tunneling in a macroscopic two-state system

Abstract
The dynamics of a dissipative, quantized macroscopic two-state system have been experimentally investigated through the measurement of tunneling transitions between the adjacent, equal-energy fluxoid states of a superconducting loop containing Josephson junctions. The tunneling rate Γ has been observed to approach zero as a power law in the temperature, giving a damping parameter α=1.44, in the incoherent relaxation regime. The predicted exponential dependence of Γ on barrier height has been quantitatively confirmed.