Wang Jianwei and Gong Qihuang of the Institute of Modern Optics, School of Physics, Peking University, in collaboration with Su Xiaolong of Shanxi University, successfully achieved the world's first "continuous variable" quantum entangled cluster states based on integrated optical quantum chips, laying an important foundation for the large-scale expansion of optical quantum chips and their applications in quantum computing, quantum networks and quantum information. The relevant scientific research results were recently published in the international academic journal Nature under the title of "Continuous variable multi-body quantum entanglement based on integrated optical quantum frequency Comb chips".

Wang Jianwei told reporters that the integrated optical quantum chip is an advanced platform that can encode, process, transmit and store optical quantum information on the micro and nano scale. "At present, with the rapid development of the chip industry, the international quantum research community is trying to overcome a problem - how to achieve large-scale quantum entanglement on optical quantum chips. The main reason is that large-scale quantum entanglement can provide a core resource state for general quantum computing and information processing."

Wang Jianwei said that entangled cluster state, as a typical multi-bit quantum entangled state, has a core position in quantum information science. And the core of the universal optical quantum computing chip lies in this, namely the on-chip quantum entangled cluster state. Previously, the optical quantum chip cluster state entanglement research mainly focused on discrete variable systems, large-scale preparation faces huge experimental difficulties, especially the continuous variable cluster state chip preparation and verification technology is still blank in the world."

After years of research, Wang Jianwei, Gong Qihuang and other research teams have for the first time realized the deterministic preparation, reconfigurable regulation and strict experimental verification of "continuous variable" entangled cluster states based on integrated optical quantum chips in the world. Qubits can be implemented on optical quantum chips by discrete variable coding and continuous variable coding respectively. In order to produce qubits with ultra-high fidelity, discrete variable coding based on single photon is usually used in the past, but the success rate of this method decreases exponentially with the increase of the number of qubits. To this end, the team innovatively adopted a continuous variable coding method based on light field, cracked the problem of "one and the other" between preparing qubits and quantum entanglement, and achieved the "deterministic" generation of quantum entangled cluster states on the chip for the first time.

"This is a new breakthrough made by Chinese scientists in the field of integrated optical quantum chip technology." Gong Qihuang said that this original achievement provides a new technical path for the preparation and manipulation of large-scale quantum entangled states, and is of great significance for promoting the practical development of quantum computing, quantum networks and quantum simulation.

"This work achieves continuous variable quantum entanglement of multiple bits on optical quantum chips for the first time, and is an important milestone in scalable optical quantum information processing," commented the reviewers of Nature.