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Title: Whirling modes and parametric instabilities in the discrete Sine-Gordon equation: Experimental tests in Josephson rings

Journal Article · · Physical Review Letters; (United States)
;  [1]; ;  [2]
  1. Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  2. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

We analyze the damped driven discrete sine-Gordon equation. For underdamped, highly discrete systems, we show that whirling periodic solutions undergo parametric instabilities at certain drive strengths. The theory predicts novel resonant steps in the current-voltage characteristics of discrete Josephson rings, occurring in the return path of the subgap region. We have observed these steps experimentally in a ring of 8 underdamped junctions. An unusual prediction, verified experimentally, is that such steps occur even if there are no vortices in the ring. Numerical simulations indicate that complex spatiotemporal behavior occurs past the onset of instability.

OSTI ID:
6641339
Journal Information:
Physical Review Letters; (United States), Vol. 74:3; ISSN 0031-9007
Country of Publication:
United States
Language:
English