  We investigate the impact of many-body interactions on group-velocity
slowdown achieved via electromagnetically induced transparency in quantum dots
using three different coupling-probe schemes (ladder, V, and Lambda,
respectively). We find that for all schemes many-body interactions have an
important impact on the slow light properties. In the case of the Lambda and V
schemes, the minimum required coupling power to achieve slow light is
significantly reduced by many-body interactions. V type schemes are found to be
generally preferable due to a favorable redistribution of carriers in energy
space.
