Superconductor-correlated metal-superconductor Josephson junctions: an optimized class for high speed digital electronics

It has long been conjectured that tuning the barrier of a Josephson junction to lie close to the metal-insulator transition will enhance the switching speed and provide optimal performance. We examine a new class of junctions, so-called SCmS junctions, where the barrier is a correlated metal (or insulator) close to the metal-insulator transition. We show that high I_cR_N products and moderate temperature derivatives of I_c can be achieved when the thickness and metallicity of the barrier is properly tuned. We believe these junctions show promise for the fastest speed digital electronics operation.