"Superluminal" tunnelling, quantum measurements and the speed of information transfer

D. Sokolovski, A. Z. Msezane, V. R. Shaginyan

Published 2004-01-26, updated 2004-06-20Version 2

We exploit the analogy between tunnelling across a potential barrier and Aharonov's weak measurements to resolve the long standing paradox between the impossibility to exceed the speed of light and the seemingly 'superluminal' behaviur of the tunnelling particle in the barrier. We demonstrate that 'superluminality' occurs when the value of the duration $\tau$ spent in the barrier is uncertain, whereas when $\tau$ is known accurately, no 'superluminal' behaviur is observed. In all cases only subluminal durations contribute to the transmission, which precludes faster-than-light information transfer, as shown by a recent experiment.