Level Statistics of Quasiparticles in Disordered Two-Dimensional Superconductors

We study level statistics in physical systems consisting of noninteracting quasiparticles in disordered superconductors that have neither time-reversal nor spin-rotation invariance. These systems are representatives of class D within the recent classification scheme of random matrix ensembles (RME). Different phase diagrams are exposed, which strongly depend on specific models of disorder. In the metallic regime the nearest neighbor spacing distribution P(s) in different models reproduces (with high accuracy) the Wigner surmise for the Gaussian unitary ensemble (GUE) expected in the presence of magnetic field whereas in the localized regime level repulsion is suppressed, reflecting only “basic” symmetries of the system and ignoring particle-hole symmetries.