On March 13, 2026, the research team headed by Professor Wang Jianwei and Professor Gong Qihuang from Peking University’s School of Physics, in collaboration with the group led by Professor Su Xiaolong from Shanxi University, published a pioneering research result in an international academic journal. This breakthrough represents the first time that the preparation, manipulation, and measurement functions of continuous-variable entangled cluster states have been successfully integrated on a single photonic quantum chip, thereby establishing a vital hardware foundation for the practical realization of large-scale photonic quantum computing and quantum networks.

The research team has achieved the integration of several key components on a single silicon nitride chip: wafer-level, high-squeezing quantum light sources; high-fidelity single-mode and dual-mode quantum gates (both achieving 99.9% fidelity); and local oscillator light sources alongside balanced homodyne interferometers for quantum measurement. Leveraging an ultra-low-loss silicon nitride platform, this chip is capable of preparing, manipulating, and measuring path-encoded four-mode continuous-variable entangled cluster states.

The chip monolithically integrates three core physical modules: the distribution and preparation of pump and local oscillator light, the deterministic generation and manipulation of squeezed states and cluster states, and a network of balanced homodyne measurement interferometers. The system demonstrates ultra-high phase stability and quantum gate fidelity without requiring any external active phase-locking mechanisms.

Additionally, the research team successfully achieved deterministic preparation, manipulation, measurement, and entanglement verification of four-mode entangled cluster states. By adjusting two squeezed light sources, they generated two pairs of dual-mode non-degenerate Einstein-Podolsky-Rosen (EPR) states, which were then interfered on high-fidelity dual-mode gates to deterministically prepare a weighted four-mode box-shaped cluster state. The squeezing levels of the four nullifiers associated with the cluster state were precisely measured, all exceeding the 3 dB threshold set by the van Loock-Furusawa criterion. Through Gaussian state tomography, the team reconstructed the covariance matrices of the quadrature components and the nullifiers, confirming the presence of a well-structured box-shaped entangled cluster state.