  It is shown that the transmission and reflection group delay times in an
asymmetric single quantum barrier are greatly enhanced by the transmission
resonance when the energy of incident particles is larger than the height of
the barrier. The resonant transmission group delay is of the order of the
quasibound state lifetime in the barrier region. The reflection group delay can
be either positive or negative, depending on the relative height of the
potential energies on the two sides of the barrier. Its magnitude is much
larger than the quasibound state lifetime. These predictions have been observed
in a microwave experiment by H. Spieker of Braunschweig University.
