Room Temperature Atomic Frequency Comb Memory for Light

Abstract

We demonstrate coherent storage and retrieval of pulsed light using the atomic frequency comb quantum memory protocol in a room temperature alkali vapour. We utilise velocity-selective optical pumping to prepare multiple velocity classes in the F = 4 hyperfine ground state of caesium. The frequency spacing of the classes is chosen to coincide with the F = 4 − F = 5 hyperfine splitting of the 6 2 P 3/2 excited state resulting in a broadband periodic absorbing structure consisting of two usually Doppler-broadened optical transitions. Weak coherent states of duration 2 ns are mapped into this atomic frequency comb with pre-programmed recall times of 8 ns and 12 ns, with multitemporal mode storage and recall demonstrated. Utilising two transitions in the comb leads to an additional interference effect upon rephasing that enhances the recall efficiency.

International Journal of Electronics and Telecommunications

“…Because of the requirement for high stability of the frequencies of different atoms with respect to each other, this method has been limited to solids at low temperatures. Recent research [50] suggests that it is possible to build a quantum memory for pulsed light based on the AFC protocol using room temperature cesium vapor. In that solution, velocity-selective optical pumping is used to prepare the frequency comb from the inhomogeneously broadened line.…”