Recently, the ultrafast optoelectronic technology research team of the school of Electronic Science and engineering of Jilin University made important progress in the field of integrated photonic chips. The research results were published online in nature Photonics (2022), doi org/10.1038/s41566-022-00976-2）。
Femtosecond laser direct writing technology is a micro nano processing technology that focuses the pulsed laser beam on the surface or inside of the material, and changes the properties of the material through the nonlinear interaction between the laser focus and the material. Thanks to its unique processing method, femtosecond laser direct writing technology can realize the processing and preparation of arbitrary three-dimensional structures, which makes it possible for on-chip three-dimensional photonic integration. However, most of the current mature design principles of on-chip photonic devices are oriented to two-dimensional chips, and there is still a lack of research on the third spatial dimension. Extending on-chip photonic integration to three-dimensional can not only provide a direct solution to improve the integration of devices in the physical space, but also provide a new degree of physical freedom for designing new on-chip photonic manipulation methods.
In view of the huge application potential of femtosecond laser direct writing 3D photonic chip, the research team proposed and successfully verified a new 3D photonic integration and control mechanism − − non Abelian weaving mechanism on the chip, which is used to realize applications such as on-chip optical quantum logic. The concept of non Abelian braiding was first proposed in the condensed matter field to realize topology protected quantum computing. Non Abelian braiding is essentially a unitary matrix transformation, so it can be realized by using the berry geometric phase matrix in the optical system.
Along this line of thought, the research team successfully realized the non Abelian braiding phenomenon with up to five photon modes on the photonic chip. Through the laser experiment and the single photon experiment, the important characteristic of the non Abelian braiding was verified respectively - the braiding results depended on the braiding sequence, and the Berry phase matrix caused by the non Abelian gauge potential was extracted through the ingenious interference experiment. The braiding mechanism has very good scalability. By expanding the number of braiding modes and braiding steps, a rich berry phase matrix can be constructed, which is oriented to applications such as on-chip optical quantum logic. In the future, by expanding the non Abelian braiding mechanism to other optical systems and using the Berry phase matrix as a new degree of freedom, researchers will be provided with more means to manipulate photons.
The first unit to complete the above research results is Jilin University. The co first authors of the paper are associate professor Zhangxulin and doctoral student Yu Feng. The co corresponding authors are associate professor Zhangxulin, associate professor tianzhennan, Professor sunhongbo of Tsinghua University and Professor maguancong of Hong Kong Baptist University. This work was supported by the National Natural Science Foundation of China.
Article links:https://www.nature.com/articles/s41566-022-00976-2
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