First multi-body nonlinear quantum interference achieved by CSU
The team of academician Guangcan Guo of the Chinese University of Science and Technology (CSU) has made important progress in the study of multi-body nonlinear quantum interference. The team's Ren Xifeng research group, in collaboration with Prof. Mario Krenn of the Max Planck Institute for Light Science in Germany, has demonstrated the international first interference of a four-photon nonlinear generation process based on an optical quantum integrated chip, and the related results were published in Optica, an authoritative academic journal on optics, on January 13.
Quantum interference is the basis of many quantum applications, especially nonlinear interference processes based on path indistinguishability have attracted increasing attention in recent years. Although two-photon nonlinear interference processes have been realized for more than two decades and have been applied in many emerging quantum technologies, it was only in 2017 that people theoretically extended the phenomenon to multi-photon processes, but no new progress has been obtained experimentally due to the need for extremely high phase stability and path coincidence requirements. The optical quantum integrated chip, with its extremely high phase stability and reconfigurability, has gradually developed into an ideal platform for demonstrating new quantum applications and developing new quantum devices, and also offers the possibility of realization for multi-photon nonlinear interference studies.
The research group of Xifeng Ren has been devoted to the development of silicon-based optical quantum integrated chips and related applications for a long time and achieved a series of important progresses: (1) the first international preparation of four-photon sources based on silicon-based photonic integrated chips (Light Sci Appl 8, 41, 2019); (2) the first preparation of frequency-combined four-photon entanglement sources (npj Quantum Inf 5, 90, 2019); (3) the first quantum logic gate operation for waveguide mode encoding (Phys. Rev. Lett., 128, 060501, 2022) and ultra-compact quantum logic gate operation (Phys. Rev. Lett., 126, 130501, 2021), etc. Based on these works, the research group, in collaboration with Prof. MarioKrenn, has demonstrated the coherent phase length and phase extinction process of the four-photon nonlinear generation process for the first time in the international arena by further cascading the structures of the multi-photon quantum light source module, the filter module and the delay module on-chip. The experimental results are shown in Fig. 1(a), and the four-photon interference visibility is 0.78, while the two-photon compliance does not observe any significant change with phase, which is consistent with the theoretical expectation. The whole experiment was done on a silicon-based integrated photonic chip with a size of only 3.8 × 0.8 mm2, as shown in Fig. 1(b).
Figure 1. (a) Quantum interferometry results; (b) Integrated optical quantum chip used to realize four-photon nonlinear quantum interference.
The results successfully extend two-photon nonlinear interference processes to multi-photon processes, laying the foundation for many new applications such as novel quantum state preparation, remote quantum metrology, and new non-local multi-photon interference effect observation. The reviewers agreed that this is an important research work and gave a high evaluation: "The chip is well-designed and contains various integrated optical components such as entangled photon source The chip is well-designed and contains various integrated optical components such as entangled photon source, an interferometer, frequency filter/combiner", "This work pushes forward the research field of integrated photonic quantum information science and technology".
Professor Ren Xifeng of the Key Laboratory of Quantum Information, CAS, and Professor Mario Krenn of the Max Planck Institute for Light Science, Germany, are the co-corresponding authors of the paper, and Lantian Feng, Distinguished Associate Researcher of the Key Laboratory of Quantum Information, CAS, is the first author of the paper. In addition, Prof. Daozin Dai and Assistant Researcher Ming Zhang from Zhejiang University provided technical support for the work. This work was supported by grants from the Ministry of Science and Technology, the State Foundation of China, the Chinese Academy of Sciences, Anhui Province, and the University of Science and Technology of China.
With links to the paper：
https://opg.optica.org/optica/fulltext.cfm?uri=optica-10-1-105&id=525159
