O'Donnell Kevin A, U'Ren Alfred B
División de Física Aplicada, Centro de Investigación Científica y de Educación Superior de Ensenada, 22860 Ensenada, Baja California, México.
Phys Rev Lett. 2009 Sep 18;103(12):123602. doi: 10.1103/PhysRevLett.103.123602.
In the process of spontaneous parametric down-conversion, photons from a pump field are converted to signal and idler photon pairs in a nonlinear crystal. The reversed process, or up-conversion of these pairs back to single photons in a second crystal, is also possible. Here, we present experimental measurements of the up-conversion rate with a controlled time delay introduced between the signal and idler photons. As a function of delay, this rate presents a full width at half maximum of 27.9 fs under our experimental conditions, and we further demonstrate that group delay dispersion of the photon pairs broadens this width. These observations are in close agreement with our calculations, thus demonstrating an ultrafast, nonclassical correlation between the signal and idler waves.
在自发参量下转换过程中，泵浦场的光子在非线性晶体中被转换为信号光子和闲置光子对。相反的过程，即这些光子对在第二个晶体中再次上转换回单光子也是可能的。在此，我们展示了在信号光子和闲置光子之间引入可控时间延迟情况下的上转换率的实验测量结果。作为延迟的函数，在我们的实验条件下，该率的半高全宽为27.9飞秒，并且我们进一步证明光子对的群延迟色散会拓宽这个宽度。这些观测结果与我们的计算结果密切相符，从而证明了信号波和闲置波之间的超快非经典相关性。
