  A quantum state light-storage, using a virtual magnetic field through the ac
Stark effect is proposed to combine the high overall storage efficiency and
large bandwidth employing room temperature atomic vapor. In this approach,
which was called the ac Stark Gradient Echo Memory (ASGEM), it has been shown
the possibility to employ about a nanosecond ac Stark pulse far detuned (about
127 THz) from D1 line of rubidium and create an atomic media with the
possibility to store a photon with about a GHz bandwidth with storage and
retrieval efficiency of more than 90%. A contour plot of efficiency as a
function of gradient field strength and optical depth, based on three-level
Maxwell- Bloch equations, simulated for a better understanding of experimental
parameter optimization.
