  Magnetic quantum periodicity in the dc voltage is observed when asymmetric
rings are switched between superconducting and normal state by a noise or ac
current. This quantum effect is used for detection of a non-equilibrium noise
with the help of a system of 667 asymmetric aluminum rings of $1 \ \mu m$ in
diameter connected in series. Any noise down to the equilibrium one can be
detected with the help of such system with enough great number of asymmetric
rings.
