Department of Physics, The Hong Kong University of Science and Technology,Clear Water Bay, Kowloon, Hong Kong, China.
Opt Lett. 2010 Jun 1;35(11):1923-5. doi: 10.1364/OL.35.001923.
We report the observation of coherent two-photon free-induction decay (FID) in a three-level Lambda system excited by a low-intensity square-modulated laser pulse. Using electromagnetically induced transparency in an Rb85 cold atomic cloud, for what we believe to be the first time, we observe FID signals with coherence time exceeding the relevant atomic excited-state natural lifetime. Because of the on-resonance enhancement, the two-photon FID signal can be observed at the falling edge without using heterodyne means.
我们报告了在由低强度方波调制激光脉冲激发的三能级 Lambda 系统中观察到的相干双光子自由感应衰减（FID）。在 Rb85 冷原子云中利用电磁感应透明，我们首次观察到相干时间超过相关原子激发态自然寿命的 FID 信号。由于共振增强，双光子 FID 信号可以在没有使用外差方法的情况下在下降沿观察到。
