  Mechanism of vibronic amplification of transport of excitons was discussed in
relation to quantum photosynthesis. Vibrones (some modes of vibrations of
molecules) are observed experimentally in photosynthetic systems. In the
present paper we discuss a model of vibronic amplification of quantum transfer
where generation of vibrones as a coherent vibrational mode is described by an
analog of semiclassical theory of laser. We consider two models --- a model of
nonequilibrium three level system with vibronic mode, and some variant of a
model of laser without inversion. We conjecture that dark states discussed in
relation to quantum photosynthesis might be related to mechanism of vibronic
"laser" without inversion which amplifies the transfer of excitons. We prove
that in presence of vibronic mode transfer rate of excitons increases and
compute dependence of the transfer rate on parameters of the model.
