Coherently enhanced Raman scattering in atomic vapor

Abstract

We present a scheme to obtain the coherently enhanced Raman scattering in atomic vapor which is induced by a spin wave initially written by a weak write laser. The enhancement of Raman scattering is dependent on the number and the spatial distribution of the flipped atoms generated by the weak write laser. Such an enhanced Raman scattering may have practical applications in quantum information, nonlinear optics and laser spectroscopy because of its simplicity.Comment: 7 pages, 4 figures, submitted to Phys. Rev.

Correlation-enhanced phase-sensitive Raman scattering in atomic vapors

“…Therefore, a simplified one-dimensional model can be enough to describe the Raman scattering. In the case of large light detuning, the atomic excited state can adiabatically be eliminated and one obtains the light-atom coupling equations governing the propagation of the quantized Stokes field and the atomic ground-state spin excitations determined by the spin wave [14,19] …”

“…The spin wave (atomic coherence) induced enhancement mechanism was studied by both theory and experiment [2,9,10,14]. When the uncorrelated light field and the spin wave are used as the initial input seeding, the enhancement is independently contributed by the light field and the spin wave, respectively.…”

“…In this paper, based on our previous work [9,10,14], we propose a scheme to enhance the Raman scattering, termed as correlation-enhanced Raman scattering (CERS). In the scheme, a pump field leads to spontaneous emission of the Stokes field, accompanying with the generation of atomic spin waves.…”

Extracting the phase information from atomic memory by intensity correlation measurement

“…After the writing process, a read field R is sent into the atomic ensemble. This process is the enhanced Raman scattering [21,22], taking R 1 field for example, the Stokes field S R 1 starts from the stimulated emission with the pre-built atomic spin wave a 1 as the seed, the corresponding phase relation is ϕ S R1 = ϕ R 1 − ϕ a 1 . So the Raman scattering of R 1 field can be regarded as the read process: reading out the phase information from the previously built atomic spin wave a 1 into S R1 field with ϕ S R1 = ϕ R 1 − ϕ W 1 + ϕ S W 1 − θ m .…”

“…1, we first write a certain phase (denoted as the memory phase θ m in Fig. 1(a)) into the atomic ensemble by Raman scattering with W 1 field, and then read out by a method of enhanced Raman scattering [21,22] with R 1 field. As is well-known, the Raman scattering in 87 Rb atoms with a Λ-shaped energy level is a three-wave mixing process involving a write field W , a Stokes field field for example, the Stokes field starts from the spontaneous emission with an arbitrary phase ϕ S W 1 .…”