Fedrizzi Alessandro, Herbst Thomas, Poppe Andreas, Jennewein Thomas, Zeilinger Anton
Opt Express. 2007 Nov 12;15(23):15377-86. doi: 10.1364/oe.15.015377.
We demonstrate a wavelength-tunable, fiber-coupled source of polarization- entangled photons with extremely high spectral brightness and quality of entanglement. Using a 25 mm PPKTP crystal inside a polarization Sagnac interferometer we detect a spectral brightness of 273000 pairs (s mW nm)(-1), a factor of 28 better than comparable previous sources while state tomography showed the two-photon state to have a tangle of T = 0.987. This improvement was achieved by use of a long crystal, careful selection of focusing parameters and single-mode fiber coupling. We demonstrate that, due to the particular geometry of the setup, the signal and idler wavelengths can be tuned over a wide range without loss of entanglement.
我们展示了一种波长可调谐、光纤耦合的偏振纠缠光子源，其具有极高的光谱亮度和纠缠质量。通过在偏振萨格纳克干涉仪内部使用一块25毫米的周期极化磷酸钛氧钾（PPKTP）晶体，我们检测到光谱亮度为273000对/（秒·毫瓦·纳米），比之前类似的光源高出28倍，同时态层析成像表明双光子态的纠缠度T = 0.987。这种改进是通过使用长晶体、精心选择聚焦参数以及单模光纤耦合实现的。我们证明，由于该装置的特殊几何结构，信号光和闲置光的波长可以在很宽的范围内调谐而不会损失纠缠。
