  We investigate the ground state of the irrationally frustrated Josephson
junction array with controlling anisotropy parameter \lambda\ 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 \lambda\ and is incommensurate with the substrate lattice.
Approaching the isotropic point, \lambda=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.
