  We consider the problem of pulsed biexciton preparation in a quantum dot and
show that a pulse-sequence with a simple on-off-on modulation can achieve
complete preparation of the target state faster than the commonly used constant
and hyperbolic secant pulses. The durations of the pulses composing the
sequence are obtained from the solution of a transcendental equation.
Furthermore, using numerical optimal control, we demonstrate that for a wide
range of values of the maximum pulse amplitude, the proposed pulse-sequence
prepares the biexciton state in the numerically obtained minimum time, for the
specific system under consideration. We finally show with numerical simulations
that, even in the presence of dissipation and dephasing, high levels of
biexciton state fidelity can be generated in short times.
