ARE ANOMALOUSLY SHORT TUNNELING TIMES MEASURABLE

Low and Mende have analyzed the conditions that would make possible an actual measurement of an anomalously short traversal time through a p otential barrier concluding that such a measurement cannot be made bec ause it is not possible to describe the tunnelling of a wave packet in itially close to the barrier by the ''usual wave packet space time ana lysis''. We complement this work in several ways: It is argued that th e described failure of the usual formalism occurs under a set of too r estrictive conditions, some of them not physically motivated, so it do es not necessarily imply the impossibility of such a measurement. Howe ver, by retaining only conditions well motivated on physical grounds w e have performed a systematic numerical check which shows that the con clusion by Low and Mende is indeed generally valid. It is shown that, as speculated by Low and Mende, the process is dominated by over the b arrier transmission. (C) 1996 Academic Press, Inc.