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SUMMARY:Fusion of Relativistic Vortices in Josephson Arrays - Prof. Alexey
  Ustinov
DTSTART:20060510T151500Z
DTEND:20060510T163000Z
UID:TALK4657@talks.cam.ac.uk
CONTACT:Duncan Simpson
DESCRIPTION:I will talk about our recent experimental observation of very 
 fast dynamically stable 4-pi vortices in arrays of parallel-connected smal
 l Josephson junctions [1]. Dynamically stable multiple kinks in discrete s
 ine-Gordon systems were predicted theoretically more than 20 years ago but
  they have been never seen in experiments until now. By measuring the curr
 ent-voltage characteristics of specially designed Josephson arrays\, we ob
 serve propagation of 4-pi-kinks in the form of fast particle-like Josephso
 n vortices. These multiple kinks carry magnetic flux equal to two magnetic
  flux quanta. At the same value of the bias current\, the velocity of 4-pi
  vortices is about 20% higher than the velocity of ordinary 2-pi vortices.
  When reducing the bias current\, a 4-pi vortex dissociates into a pair of
  two spatially separated ordinary 2-pi vortices of the same polarity movin
 g at a constant distance from each other. Such metastable bunched states a
 re formed due to interaction between vortices through their oscillatory ta
 ils.\n\n[1] J. Pfeiffer\, M. Schuster\, A. A. Abdumalikov\, and A. V. Usti
 nov\,Phys. Rev. Lett. 96\, 034103 (2006)\n
LOCATION:Pippard Lecture Theatre\, Cavendish Laboratory\, Department of Ph
 ysics
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