J. Phys. I France 4 (1994) 1783-1789
Complex-barrier tunnelling timesFabio Raciti and Giovanni Salesi
Dipartimento di Fisica, Università Statale di Catania, Catania, Italy LN F.N., Sezione di Catania, Catania, Italy
(Received 24 August 1994, receved in final form 9 September 1994, accepted 20 September 1994)
In this paper we calculate the analytic expression of the phase time for the scattering of an electron off a complex square barrier. As is well known the (negative) imaginary part of the potential takes into account, phenomenologically, the absorption. We investigate the Hartman-Fletcher effect, and find that it is suppressed by the presence of a (non negligible) imaginary potential. In fact, when a suffficiently large absorption is present, the asymptotical transmission speed is finite. Actually, the tunnelling time does increase linearly with the barrier width. A recent optical experiment seems to be in agreement with our theoretical expectation.
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