Relationship between the Noise-Induced Persistent Current and the Dephasing Rate

ac noise in disordered conductors causes both dephasing of the electron wave functions and a dc current around a mesoscopic ring. We demonstrate that the dephasing rate τ^-1_ϕ in long wires and the dc current , induced by the same noise and averaged over an ensemble of small rings, are connected in a remarkably simple way: τ_ϕ = C_βe. Here e is an electron charge, and the constant C_β~1 depends on the Dyson symmetry class. The relationship seems to agree reasonably with experiments. This suggests that the two puzzles, anomalously large persistent current and the low-temperature saturation of the dephasing, may have a common solution.