Mesoscopic circuits with charge discreteness: quantum current magnification for mutual inductances

Current magnification is studied for a system of two rings with external magnetic flux; we have considered, in addition to self-inductance, a mutual inductance between the rings. The system is studied using a method recently proposed by Li and Chen, which takes into account the charge quantization of the system, allowing for a simplified description. We find that, for some values of the external flux enclosed by one of the rings, quantum current magnification exists in the other ring. This magnification effect is a purely quantum phenomenon, which is given here an alternative explanation, different from the detailed quantum-mechanical explanation.