Quantum beating in the conductance of ballistic rings

We propose and demonstrate experimentally a novel configuration for observing spin interference effects in the conductance of quantum rings. Our configuration, in which the conducting ring and the tangential current lead form a single collimating contact, precludes spin rotation in the contact region. We have observed the spin quantum beating in the Aharonov–Bohm (AB) conductance oscillations. This beating is the result of a superposition of two independent interference signals associated with the intrinsic spin–orbit interactions. Our work provides conclusive evidence of the spin Berry phase in the ring conductance.