VOLTAGE RECTIFICATION IN A DRIVEN ASYMMETRIC SQUID

We argue that the phase across an asymmetric de SQUID threaded by a ma gnetic flux can experience a ratchet (periodic and asymmetric) potenti al. Under an external ac current, a rocking ratchet mechanism operates whereby one sign of the time derivative of the phase is favored. We s how that there exists a range of parameters in which a fixed sign of t he average voltage across the ring occurs, regardless of the sign of t he external current de component.