  Using collective atom phase control a population inversion-free photon echo
scheme has been studied for quantum memory applications. For the inversion-free
photon echoes a double rephasing method is combined with optical locking, where
the optical locking coherently controls each atom phase excited by weak data
pulses. As a result, intensity flattened, normally ordered, storage
time-extended, and noise-free photon echoes are obtained.
