  We study the potential for controlled transfer of population to the biexciton
state of a semiconductor quantum dot coupled with a metal nanoparticle, under
the influence of an electromagnetic pulse with hyperbolic secant shape, and
derive analytical solutions of the density matrix equations, for both zero and
nonzero biexciton energy shift. These solutions lead to efficient transfer to
the biexciton state, for various interparticle distances, including relatively
small values. In certain cases, when the distance between the two particles is
small, the transfer of population is strongly modified because of the influence
of surface plasmons to the excitons, and the effect is more pronounced for
shorter pulses. The hybrid snanostructure that we study has been proposed for
generating efficiently polarization-entangled photons, thus the successful
biexciton state preparation considered here is expected to contribute in this
line of research.
