Non equilibrium superconductivity by using quasi-particle injection in stacked tunnel junctions

An experimental study of quasi-particle trapping in proximised Nb/Al layers with different Al thicknesses is presented using symmetrical 3-terminal stacked double tunnel junctions. The experimental tunnelling efficiency of such devices is measured at temperatures down to 1.2 K for different injection current rates. The role of Al layers in the intermediate electrode is discussed in terms of effective non equilibrium processes. The agreement with existing theories on nonequilibrium in such proximity structures makes these results important toward a better understanding of the underlying physics in high resolution particle spectrometers.