Escape from the zero-voltage state in hysteretic dc-SQUIDs with different dimensionless inductance

We studied the escape process from the zero-voltage state to the running st ate in hysteretic dc-SQUIDs made with trilayer Nb-AlOx-Nb junctions. We ana lyze the experimental results, according to the thermal activation model, f ar devices having similar parameters except for the dimensionless inductanc e beta (L) which however is always very small. The interest in hysteretic d c-SQUIDs is in the possibility of using them to perform non-invasive measur ements of the flux states in rf-SQUIDs: this achievement would be very impo rtant both in tests of macroscopic quantum properties of SQUIDs and in meas urements on a class of quantum bits that has been recently proposed, based on magnetic flux states in SQUIDs.