Chen Changchen, Heyes Jane E, Hong Kyung-Han, Niu Murphy Yuezhen, Lita Adriana E, Gerrits Thomas, Nam Sae Woo, Shapiro Jeffrey H, Wong Franco N C
Opt Express. 2019 Apr 15;27(8):11626-11634. doi: 10.1364/OE.27.011626.
We use pulsed spontaneous parametric down-conversion in KTiOPO , with a Gaussian phase-matching function and a transform-limited Gaussian pump, to achieve near-unity spectral purity in heralded single photons at telecommunication wavelength. Theory shows that these phase-matching and pump conditions are sufficient to ensure that a biphoton state with a circularly symmetric joint spectral intensity profile is transform limited and factorable. We verify the heralded-state spectral purity in a four-fold coincidence measurement by performing Hong-Ou-Mandel interference between two independently generated heralded photons. With a mild spectral filter we obtain an interference visibility of 98.4±1.1% which corresponds to a heralded-state purity of 99.2%. Our heralded photon source is potentially an essential resource for measurement-based quantum information processing and quantum network applications.
我们在磷酸钛氧钾（KTiOPO₄）中使用脉冲自发参量下转换，采用高斯相位匹配函数和变换极限高斯泵浦，以在电信波长的预示单光子中实现接近单位的光谱纯度。理论表明，这些相位匹配和泵浦条件足以确保具有圆对称联合光谱强度分布的双光子态是变换极限且可分解的。我们通过在两个独立产生的预示光子之间进行洪-欧-曼德尔干涉，在四重符合测量中验证了预示态的光谱纯度。使用一个温和的光谱滤波器，我们获得了98.4±1.1%的干涉可见度，这对应于99.2%的预示态纯度。我们的预示光子源可能是基于测量的量子信息处理和量子网络应用的重要资源。
