N. Gronbechjensen et al., FLUXON BUNCHING IN SUPERCURRENT-COUPLED JOSEPHSON-JUNCTIONS, Physical review. B, Condensed matter, 48(9), 1993, pp. 6353-6359
We investigate analytically and numerically the interaction between fl
uxons of different Josephson junctions coupled through Cooper-pair tun
neling. We find that the supercurrent interaction gives rise to attrac
tion between fluxons regardless of their polarity, although fluxons of
different polarity are found to interact with a binding energy of an
order of magnitude larger than between unipolar fluxons. When bias cur
rent is applied to a system of two coupled junctions we can analytical
ly evaluate the range in the difference of the bias currents for which
fluxons are bound. The differences in interaction between fluxons of
equal and opposite polarity are discussed. Numerical simulations of co
upled sine-Gordon equations agree very well with the analytical predic
tions.