  When the excitation of carriers in real space is focused down to the
nanometer scale, the carrier system can no longer be viewed as homogeneous and
ultrafast transport of the excited carrier wave packets occurs. In
state-of-the-art semiconductor structures like low-dimensional heterostructures
or monolayers of transition metal dichalcogenides, the Coulomb interaction
between excited carriers becomes stronger due to confinement or reduced
screening. This demands a fundamental understanding of strongly interacting
electrons and holes and the influence of Coulomb correlations. To study the
corresponding particle dynamics in a controlled way we consider a system of up
to two electron-hole pairs exactly within a wave function approach. We show
that the excited wave packets contain a non-trivial mixture of free particle
and excitonic states. We further scrutinize the influence of Coulomb
interaction on the wave packet dynamics revealing its different role for below
and above band-gap excitation.
