Thermal activation and macroscopic quantum tunneling in a DC squid

F. Sharifi, J. L. Gavilano, D. J. Van Harlingen

Research output: Contribution to journalArticlepeer-review


The authors report measurements of the transition rate from zero-voltage metastable minima in the two-dimensional potential of a DC SQUID (superconducting quantum interference device) as a function of applied flux and temperature. A crossover is observed from thermally activated escape to macroscopic quantum tunneling at a critical temperature that is a strong function of the bias flux. The macroscopic quantum tunneling rate is substantially reduced by damping, which also broadens the crossover region. The authors unexpectedly observed thermal rates that are significantly suppressed from those predicted by the classical two-dimensional thermal activation model, as if the potential barrier for activation were effectively enhanced. They discuss possible explanations for this result, based on the interaction of the macroscopic degrees of freedom in the device and energy level quantization effects.

Original languageEnglish (US)
Pages (from-to)1174-1177
Number of pages4
JournalIEEE Transactions on Magnetics
Issue number2
StatePublished - Mar 1989

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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