Shot-noise measurements in normal-metal-superconductor junctions and the semiclassical theory

We present an analysis of shot-noise measurements in normal-metal-superconductor (NS) junctions [X. Jehl et al., Nature (London) 405, 50 (2000)], based on a recent semiclassical theory. The first calculations at zero temperature assuming quantum coherence predicted shot noise in NS contacts to be doubled with respect to normal contacts. The semiclassical approach gives the opportunity to compare data and theory quantitatively at finite voltage and temperature. The doubling of shot noise is predicted up to the superconducting gap, as already observed, confirming that phase coherence is not necessary. An excellent agreement is also found above the gap where the noise follows the normal case.