  The carrier-phonon interaction in semiconductor quantum dots can greatly
affect the optical preparation of the excited state. For resonant excitation
used in the Rabi preparation scheme, the polaron is formed accompanied by the
emission of a phonon wave packet, leading to a degradation of preparation
fidelity. In this paper, phonon wave packets for different coherent excitation
schemes are analyzed. One example is the adiabatic rapid passage scheme relying
on a chirped excitation. Here, also a phonon wave packet is emitted, but the
preparation fidelity can still be approximately unity. A focus is on the phonon
impact on a recently proposed swing-up scheme, induced by two detuned pulses.
Similar to the Rabi scheme, a degradation and a phonon wave packet emission is
found, despite the detuning. If the swing-up frequency coincides with the
maximum of the phonon spectral density, a series of wave packets is emitted
yielding an even stronger degradation. The insight gained from our results will
further help in designing an optimal preparation scheme for quantum dots.
