Tuning a Josephson junction through a quantum critical point - art. no. 054511

We tune the barrier of a Josephson junction through a zero-temperature meta l-insulator transition and study the thermodynamic behavior of the junction in the proximity of the quantum-critical point. We examine a short-coheren ce-length superconductor and a barrier (that is described by a Falicov-Kimb all model) using the local approximation and dynamical mean-field theory. T he inhomogeneous system is self-consistently solved by performing a Fourier transformation in the planar momentum and exactly inverting the remaining one-dimensional matrix with the renormalized perturbation expansion. Our re sults show a delicate interplay between oscillations on the scale of the Fe rmi wavelength and pair-field correlations on the scale of the coherence le ngth, variations in the current-phase relationship, and dramatic changes in the characteristic voltage as a function of the barrier thickness or corre lation strength (which can lead to an "intrinsic" pinhole effect).