Hysteretic noise in dc SQUIDs

The energy resolution per bandwidth ε has been calculated on a hybrid computer for large asymmetry factors a and for large McCumber damping parameters β. An increase of a from 1 to 4 decreases the energy resolution ε to 65%. For large damping parameters β the low frequency voltage noise SUOincreases approximately exponentially with β depending strongly on the bias current IG. A proper choice of the bias current yields a small ε even for a large damping parameter β = 6.