Volume 80, Number 1, October 2007
|Number of page(s)||5|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||17 September 2007|
Why macroscopic quantum tunnelling in Josephson junctions differs from tunnelling of a quantum particle
Frontier Research System, The Institute of Physical and Chemical Research (RIKEN) - Wako-shi, Saitama, 351-0198, Japan
2 Institute for Theoretical and Applied Electrodynamics Russian Academy of Sciences - 125412 Moscow, Russia
3 Department of Physics, Loughborough University - Loughborough LE11 3TU, UK
4 MCTP, CSCS, Department of Physics, University of Michigan - Ann Arbor, MI 48109-1040, USA
Accepted: 17 August 2007
We show that the macroscopic quantum tunnelling of a fluxon in a Josephson junction cannot be described, even qualitatively, as the tunnelling of a quantum particle in a potential , where the phase difference φ plays the role of particle position, if the length of the junction d exceeds a fluxon length. We calculate the probability per unit time of tunnelling (or escape rate), , which has a form Γ = A exp . In contrast to particles, where the B is proportional to d, our field-theory predicts a different behavior of B for either usual, 0–, or stacks of Josephson junctions, giving rise to a renormalization of by many orders of magnitude.
PACS: 74.50.+r – Tunneling phenomena; point contacts, weak links, Josephson effects
© Europhysics Letters Association, 2007
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