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对非线性晶体参量下转换过程所产生的纠缠光子对的一路光子进行测量, “宣布”式地在另一路获得单光子, 是制备单光子源的一种重要途径. 其中, 核心的问题是如何得到较高的宣布效率. 本文以I类相位匹配偏硼酸钡 (β-BaB2O4, BBO)非线性晶体参量下转换过程中所产生的偏振纠缠光子对为例, 通过研究其纠缠特性来对宣布效率与宣布测量基选择的相关性进行理论分析. 进而, 利用光纤偏振分束器和三个单光子探测器搭建的扩展型Hanbury Brown-Twiss实验装置, 实现了宣布效率的测量. 实验结果表明, 宣布效率确实与宣布基选择有关: 对本系统的纠缠光子源而言, 采用
|+/-\rangle 偏振宣布基所得到的宣布效率比采用|H/V\rangle 偏振宣布基所得到的宣布效率提高了大约4%.The method by measuring one photon of an entangled two-photon pair to simultaneously herald another photon as the single photon, is one of the important ways to prepare the desired single-photon source. However, achieving high herald efficiency is still an open problem. In this paper, with the polarization entangled photon pairs generated by the parametric down-conversion process in the I-type phase-matched BBO (β-BaB2O4) nonlinear crystal, we investigate how the herald efficiency of the single-photon along the ideal path depends on the selection of the heralded basis of the photon in the signal path. An extended Hanbury-Brown-Twiss experimental system is built with a fiber polarizing beam splitter and three single-photon detectors, to experimentally measure the herald efficiency of the heralded single-photon source. Our results show that with the present polarization entangled-photon system whose quality is relatively low, the herald efficiency with the |+/-\rangle heralded basis is enhanced 4% compared with that with the|H/V\rangle heralded basis.-
Keywords:
- parametric down conversion /
- entangled photon pairs /
- heralded single photon source /
- heralded efficiency
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中国物理学会期刊
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