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 multi-photon 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.
@article{arxiv.1812.02368,
title = {Generation of a frequency-degenerate four-photon entangled state using a silicon nanowire},
author = {Lan-Tian Feng and Ming Zhang and Zhi-Yuan Zhou and Yang Chen and Ming Li and Dao-Xin Dai and Hong-Liang Ren and Guo-Ping Guo and Guang-Can Guo and Mark Tame and Xi-Feng Ren},
journal= {arXiv preprint arXiv:1812.02368},
year = {2019}
}