We have studied the transition rate from the zero-voltage state in a dc SQUID as a function of applied flux and temperature. We observe a crossover from thermal activation to macroscopic quantum tunneling at a flux-dependent temperature. The thermal rates are significantly suppressed, suggesting that the potential barrier for escape is effectively enhanced by the interaction of the macroscopic degrees of freedom in the two-dimensional dc SQUID potential.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering