Persistent currents in a Moebius ladder: A test of interchain coherence of interacting electrons

Persistent currents in a Moebius ladder are shown to be very sensitive to the effects of intrachain interactions on the hopping of electrons between chains. Their periodicity as a function of flux is doubled for strong enough repulsive interactions because electrons cannot hop coherently between the chains and have to travel along the full edge of the Moebius ladder, thus encircling the flux twice. Mesoscopic devices that should enable one to observe these effects are proposed.