  We demonstrate that an optically driven spin of a carrier in a quantum dot
undergoes indirect dephasing via conditional optically induced charge evolution
even in the absence of any direct interaction between the spin and its
environment. A generic model for the indirect dephasing with a three-component
system with spin, charge, and reservoir is proposed. This indirect decoherence
channel is studied for the optical spin manipulation in a quantum dot with a
microscopic description of the charge-phonon interaction taking into account
its non-Markovian nature.
