Paper detail

Transition by Breaking of Analyticity in the Ground State of Josephson Junction Arrays as a Static Signature of the Vortex Jamming Transition

We investigate the ground state of the irrationally frustrated Josephson junction array with controlling anisotropy parameter λ that is the ratio of the longitudinal Josephson coupling to the transverse one. We find that the ground state has one dimensional periodicity whose reciprocal lattice vector depends on λ and is incommensurate with the substrate lattice. Approaching the isotropic point, λ=1 the so called hull function of the ground state exhibits analyticity breaking similar to the Aubry transition in the Frenkel-Kontorova model. We find a scaling law for the harmonic spectrum of the hull functions, which suggests the existence of a characteristic length scale diverging at the isotropic point. This critical behavior is directly connected to the jamming transition previously observed in the current-voltage characteristics by a numerical simulation. On top of the ground state there is a gapless, continuous band of metastable states, which exhibit the same critical behavior as the ground state.