Integrated photonics is becoming an ideal platform for generating two-photon entangled states with high brightness, high stability, and scalability. This high brightness and high quality of photon pair sources encourages researchers further to study and manipulate multiphoton entangled states. Here, we experimentally demonstrate frequency-degenerate four-photon entangled state generation based on a single silicon nanowire 1 cm in length. The polarization encoded entangled states are generated with the help of a Sagnac loop using additional optical elements. The states are analyzed using quantum interference and state tomography techniques. As an example, we show that the generated quantum states can be used to achieve phase super-resolution. Our work provides a method for preparing indistinguishable multi-photon entangled states and realizing quantum algorithms in a compact on-chip setting.

集成光子学正成为生成具有高亮度，高稳定性和可伸缩性的两个光子纠缠态的理想平台。光子对源的这种高亮度和高质量鼓励研究人员进一步研究和操纵多光子纠缠态。在这里，我们实验性地证明了基于长度为1 cm的单硅纳米线的频率简并四光子纠缠态生成。偏振编码纠缠态是在Sagnac回路的帮助下使用其他光学元件生成的。使用量子干涉和状态层析成像技术来分析状态。作为一个例子，我们表明所产生的量子态可用于实现相位超分辨率。