Researchers from the School of Physics at Nanjing University, led by Professors Xiaosong Ma and Shining Zhu, have unveiled a novel method for generating quantum entangled states. By harnessing the path identity of photons, their approach achieves entanglement between independent photons without relying on pre-generated entangled states, Bell-state measurements, or the detection of all auxiliary photons—requirements that are essential for entanglement swapping. This indicates that the two methods differ in their underlying physical principles. The protocol was identified and optimized with the assistance of PyTheus, an AI-driven quantum optics design framework that converts complex experiments into graph representations, significantly streamlining the design process. This novel approach reduces the experimental demands of quantum systems, offering a more efficient pathway for advancing quantum information processing technologies.

Figure (a) Entanglement generation through path identity. (b) Entanglement generation through path identity with the detection of only one ancillary photon.

Publication link:

Kai Wang, Zhaohua Hou, Kaiyi Qian, Leizhen Chen, Mario Krenn, Shining Zhu, and Xiao-Song Ma, Entangling Independent Particles by Path Identity, Phys. Rev. Lett. 133, 233601 (2024)

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.133.233601