Evidence of two-dimensional macroscopic quantum tunneling of a current-biased dc SQUID

The escape probability out of the superconducting state of a hysteretic dc SQUID has been measured at different values of the applied magnetic flux. At low temperatures, the escape current and the width of the probability distribution are temperature independent but they depend on flux. Experimental...

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Bibliographic Details
Published in:Physical review letters 2003-10, Vol.91 (15), p.158301-158301, Article 158301
Main Authors: Balestro, F, Claudon, J, Pekola, J P, Buisson, O
Format: Article
Language:English
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Summary:The escape probability out of the superconducting state of a hysteretic dc SQUID has been measured at different values of the applied magnetic flux. At low temperatures, the escape current and the width of the probability distribution are temperature independent but they depend on flux. Experimental results do not fit the usual one-dimensional macroscopic quantum tunneling (MQT) law but are perfectly accounted for by the two-dimensional MQT behavior as we propose here. Near zero flux, our data confirms the recent MQT observation in a dc SQUID [Phys. Rev. Lett. 89, 98301 (2002)]].
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.91.158301