Quantum glass transition in a periodic long-range Josephson array

We show that the ground state of a periodic long-range Josephson array frus trated by a magnetic field is a glass for sufficiently large Josephson ener gies despite the absence of quenched disorder. Like superconductors, this g lass state has non-zero phase stiffness and Meissner response; for lower Jo sephson energies the glass "melts" and the ground state loses its phase sti ffness and becomes insulating. We find the critical scaling behavior near t his quantum phase transition: the excitation gap vanishes as (J-J(c))(2), a nd the frequency-dependent magnetic susceptibility behaves as chi(omega)pro portional to root omega ln omega. (C) 1999 American Institute of Physics. [ S1063-7761(99)02310-0].