  Tunneling, though a physical reality, is shrouded in mystery. Wave packets
cannot be constructed under the barrier and group velocity cannot be defined.
The tunneling particle can be observed on either sides of the barrier but its
properties under the barrier has never been probed due to several problems
related to quantum measurement. We show that there are ways to bypass these
problems in mesoscopic systems and one can even derive an expression for the
quantum mechanical current under the barrier. A general scheme is developed to
derive this expression for any arbitrary system. One can use mesoscopic
phenomenon to subject the expression to several theoretical and experimental
cross checks. For demonstration we consider an ideal 1D quantum ring with
Aharonov-Bohm flux $\Phi$, connected to a reservoir. It gives clear evidence
that propagation occur under the barrier resulting in a current that can be
measured non-invasively and theoretically cross checked. Time reversed states
play a role but there is no evidence of violation of causality. The evanescent
states are known to be largely stable and robust against phase fluctuations
making them a possible candidate for device applications and so formalizing
current under barrier is important.
