Hidden and unhidden information in quantum tunneling

We discuss the claim that when the peak of a tunneling wave packet appears on the far side of a barrier sooner than would be allowed by causal propagation of the incident peak, this must be interpreted to mean that the transmitted particles originate toward the leading edge of the incident peak. We examine the status of information about where in a wave packet a particle is, both in terms of Bohm's deterministic picture of quantum mechanics and in terms of a recently proposed Gedankenexperiment. We find that while there are very real senses in which this interpretation makes sense, attempts to explicitly bring out this extra information in the form of quantum-mechanical observables necessarily fail. It therefore remains "hidden" information, which we can deduce indirectly from multiple experiments or from the principle of causality, but which we can never observe directly in a single experiment.