Edamatsu Keiichi, Oohata Goro, Shimizu Ryosuke, Itoh Tadashi
Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan.
Nature. 2004 Sep 9;431(7005):167-70. doi: 10.1038/nature02838.
Entanglement is one of the key features of quantum information and communications technology. The method that has been used most frequently to generate highly entangled pairs of photons is parametric down-conversion. Short-wavelength entangled photons are desirable for generating further entanglement between three or four photons, but it is difficult to use parametric down-conversion to generate suitably energetic entangled photon pairs. One method that is expected to be applicable for the generation of such photons is resonant hyper-parametric scattering (RHPS): a pair of entangled photons is generated in a semiconductor via an electronically resonant third-order nonlinear optical process. Semiconductor-based sources of entangled photons would also be advantageous for practical quantum technologies, but attempts to generate entangled photons in semiconductors have not yet been successful. Here we report experimental evidence for the generation of ultraviolet entangled photon pairs by means of biexciton resonant RHPS in a single crystal of the semiconductor CuCl. We anticipate that our results will open the way to the generation of entangled photons by current injection, analogous to current-driven single photon sources.
纠缠是量子信息与通信技术的关键特性之一。产生高度纠缠光子对最常用的方法是参量下转换。短波长纠缠光子对于在三四个光子之间产生进一步的纠缠是很有必要的,但利用参量下转换来产生具有适当能量的纠缠光子对却很困难。一种有望适用于产生此类光子的方法是共振超参量散射(RHPS):通过电子共振三阶非线性光学过程在半导体中产生一对纠缠光子。基于半导体的纠缠光子源对于实际的量子技术也将具有优势,但在半导体中产生纠缠光子的尝试尚未成功。在此,我们报告了通过双激子共振RHPS在半导体CuCl单晶中产生紫外纠缠光子对的实验证据。我们预计,我们的结果将为通过电流注入产生纠缠光子开辟道路,类似于电流驱动的单光子源。