  We investigate the large-N behaviour of simple examples of supersymmetric
interactions for fermions on a lattice. Witten's supersymmetric quantum
mechanics and the BCS model appear just as two different aspects of one and the
same model. For the BCS model, supersymmetry is only respected in a coherent
superposition of Bogoliubov states. In this coherent superposition mesoscopic
observables show better stability properties than in a Bogoliubov state.
