Issue |
EPL
Volume 80, Number 1, October 2007
|
|
---|---|---|
Article Number | 17009 | |
Number of page(s) | 5 | |
Section | Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties | |
DOI | https://doi.org/10.1209/0295-5075/80/17009 | |
Published online | 17 September 2007 |
Why macroscopic quantum tunnelling in Josephson junctions differs from tunnelling of a quantum particle
1
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
Received:
14
June
2007
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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