  Coherent manipulation of quantum states is of crucial importance in accurate
control of a quantum system. A fundamental goal is coherently transferring the
population of a desired state with near-unit fidelity. For this propose, we
theoretically demonstrate a novel coherent double-stimulated Raman adiabatic
passage (STIRAP) in a three-level $\Lambda$-type system for realizing the
switch of unequal initial preparations on two ground states. This operation
uses single optical pulse sequence accomplishing both bright-STIRAP and
dark-STIRAP process, in which the intermediate-level detuning and the pulse
delay must be given an optimal adjustment. Besides, owing to the imperfection
of double-STIRAP transition, the sensitivity of the switch fidelity with
respect to the spontaneous loss from the intermediate state, to the pulse
amplitude and to the population difference, are also discussed. This work
suggests a simple and experimentally-feasible all-optical approach to switch
the superposition quantum state, serving as one-step closer to the goal of
coherent manipulation of quantum systems.
