INTRINSIC DISSIPATIVE FLUCTUATION RATE IN MESOSCOPIC SUPERCONDUCTING RINGS

The rate at which dissipative fluctuations occur in narrow superconduc ting rings is considered within the Little-Langer-Ambegaokar-McCumber- Halperin framework. The mesoscopic regime, in which the ring circumfer ence L does not greatly exceed the correlation length xi, is specifica lly addressed. In this regime, significant differences arise between m odels that mimic voltage and current sources, the former (latter) exhi biting corrections to the fluctuation rate algebraic in xi/L (exponent ially small in L/xi). The theory employs Forman's elaboration of the G el'fand-Yaglom technique for computing fluctuation determinants.