Photon entanglement is the core index of the basic ability of quantum information processing. The more entangled photons are manipulated, the exponential growth of quantum information processing ability will occur. The research team of University of Science and Technology of China has realized ten-photon entanglement in the world, which can be applied to large-scale quantum information technology, indicating that China leads the research of multiphoton entanglement and interference measurement in the world. The research background is that multi-particle entanglement manipulation is the core index of quantum information processing ability. The more entangled photons are manipulated, the quantum information processing ability will increase exponentially, but at the same time, the difficulty of experimental realization will increase sharply. The Pan Jianwei team of the University of Science and Technology of China achieved and maintained the world record of multiphoton entangled state for the first time. They were internationally in 2004, 2007 and 2012 respectively

For the first time, the five-photon, six-photon and eight-photon entanglement has been manipulated, and systematically applied to quantum communication, quantum computing and other research directions, becoming the pioneer and leader in the field of multiphoton entanglement in the world.

As can be seen from Fig. 1, this optical system is complex, and the requirements for the collimation and adjustment accuracy of the optical path are relatively high. You can know something about building complex systems with multi-axis cage structure through the actual optical path diagram 2 of Figure 1:

The specific requirements of this optical system are: the system should be stable and have good collimation, and the turning point of light 450 should be realized in the collimated optical path, and the area should be limited to 600mmx600mm; The important point is that the whole system needs to be an integrated structure. Because there are three intersections in the optical path of the design in Figure 1, the system cannot be completed by using the cage structure of any other manufacturer

The multi-axis cage structure can easily meet the system requirements, as shown in Figure 3 (the intersection of three beams of light in the middle part of Figure 2). This is the most difficult part of building a system, which is difficult to achieve by using a general cage structure! However, the multi-axis cage structure can realize the intersection of three lights.