  Memory effect of non-Markovian dynamics in open quantum systems is often
believed to be beneficial for quantum information processing. In this work, we
employ an experimentally controllable two-photon open system, with one photon
experiencing a dephasing environment and the other being free from noise, to
show that non-Markovian effect may also have a negative impact on quantum tasks
such as remote state preparation: For a certain period of controlled time
interval, stronger non-Markovian effect yields lower fidelity of remote state
preparation, as opposed to the common wisdom that more information leads to
better performance. As a comparison, a positive non-Markovian effect on the RSP
fidelity with another typical non-Markovian noise is analyzed. Consequently,
the observed dual character of non-Markovian effect will be of great importance
in the field of open systems engineering.
