National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Phys Rev Lett. 2013 May 24;110(21):210401. doi: 10.1103/PhysRevLett.110.210401. Epub 2013 May 21.
We present a semiclassical theoretical framework on light-wave mixing and scattering with single-component quantum gases. We show that these optical processes originating from elementary excitations with dominant collective atomic recoil motion are stimulated Raman or hyper-Raman in nature. In the forward direction the wave-mixing process, which is the most efficient process in normal gases, is strongly reduced by the condensate structure factor even though the Bogoliubov dispersion relation automatically compensates the optical-wave phase mismatch. In the backward direction, however, the free-particle-like condensate structure factor and Bogoliubov dispersion result in highly efficient light-wave mixing and collective atomic recoil motion that are enhanced by a stimulated hyper-Raman gain and a very narrow two-photon motional state resonance.
我们提出了一个关于单组份量子气体中光波混合和散射的半经典理论框架。我们表明，这些源自于具有主导集体原子反冲运动的基本激发的光学过程本质上是受激拉曼或超拉曼过程。在正向方向上，波混合过程（在正常气体中效率最高的过程）会被凝聚体结构因子大大削弱，尽管玻色-爱因斯坦凝聚体的色散关系会自动补偿光学波的相位失配。然而，在反向方向上，自由粒子状的凝聚体结构因子和玻色-爱因斯坦凝聚体的色散导致高效的光波混合和集体原子反冲运动，这是受激超拉曼增益和非常窄的双光子运动状态共振增强的结果。
