Current carried by evanescent modes and possible device application

Quantum tunneling of an electron through a classically forbidden regime has no classical analogue and several aspects of it are still not well understood. In this work we analyze electronic currents under the barrier. For this we consider a multichannel Aharonov-Bohm ring and developed a correct formalism to calculate the currents inside the ring when the states are evanescent. We also show unlike other proposed quantum devices that such currents and associated conductance are not very sensitive to changes in material parameters and thus the system can be used to build stable devices that work on magnetic and transport properties. We also study the current magnification property of the ring in presence of both propagating and evanescent states.