Current magnification effect in mesoscopic systems at equilibrium

We study the current magnification effect and associated circulating currents in mesoscopic systems at equilibrium. Earlier studies have revealed that in the presence of transport current (nonequilibrium situation), circulating currents can flow in a ring even in the absence of magnetic field. This was attributed to current magnification that is quantum mechanical in origin. We have shown that the same effect can be obtained in equilibrium systems, however, in the presence of magnetic flux. For this we have considered an one-dimensional open mesoscopic ring connected to a bubble, and the system is in contact with a single reservoir. We have considered a special case where bubble does not enclose magnetic flux, yet circulating currents can flow in it due to current magnification.