Enhanced shot noise in long quasi-diffusive S-N-S junctions

We present shot noise measurements on superconducting-normal-superconductin g junction (S-N-S) where the superconductor is Niobium and the normal condu ctor is a two-dimensional electron gas in a InAlAs/InGaAs heterojunction. T he aim of the measurements was to check the recent predictions [Phys. Rev. Lett. 83 (1999) 2050] that in the limit of incoherent multiple Andreev refl ection (I-MAR), i.e. in the elastic regime for Thouless energy much lower t han the superconducting gap, the current-voltage characteristics should be quasi-linear but I-MAR could be detected in the shot noise. (C) 2001 Elsevi er Science B.V. All rights reserved.