THE INTERPLAY OF PROXIMITY AND CHARGING EFFECTS

A superconductor connected to a normal metal by a tunnel junction indu ces a superconducting pair amplitude in the normal side. This proximit y effect is profoundly modified by the Coulomb interaction: charging e ffects caused by the small capacitance of the junctions suppress the t unneling of electrons and therefore the proximity effect. Both effects can be modulated by means of a gate voltage and show an interesting e ven-odd asymmetry due to parity effects. This offers the possibility t o modulate supercurrents. We use an effective Ginzburg-Landau formulat ion to calculate the critical current and the T-c enhancement of a nor mal wire with a finite pairing interaction connected to superconductin g islands.