Light-Wave Mixing and Scattering with Quantum Gases
Lu Deng, Chengjie Zhu, Edward W. Hagley
We present a general theoretical framework on light-wave mixing and scattering in quantum gases. We show that all such processes that originate from elementary excitations are stimulated Raman or hyper-Raman in nature. In the forward direction, the third-harmic generation originated from elementary excitation is strongly suppressed but a contribution independent of atomic centerof- motion grows as in a normal gas. In the backward direction, the third harmoni generation from electronic excitation is strongly suppressed because of the large optical wave phase mismatch. However, a highly efficient light-wave mixing process originating from elementary excitation occurs, resulting in ultra-slow light wave propagation with stimulated Raman or hyper-Raman gain, and highly efficient collective atomic recoil motion.