  For a two-level system, it is believed that a far-off-resonant driving can
not help coherent population transfer between the states. In this work, we
propose a scheme to implement the coherent transfer with far-off-resonant
driving. The scheme works well with both constant driving and Gaussian driving.
The total time to finish population transfer is also minimized by optimizing
the detuning and coupling constants. We find that the scheme is sensitive to
spontaneous emission much more than dephasing. It might find potential
applications in X-ray quantum optics and population transfer in Rydberg atoms
as well.
