Overview of the Jiuzhang Photonic Quantum Computing Series and the Frontier of Gaussian Boson Sampling

The realization of quantum computational advantage represents a fundamental shift in the capabilities of information processing, marking the transition from theoretical quantum mechanics to the era of practical, large-scale quantum devices. At the forefront of this transition is the Jiuzhang series, a lineage of photonic quantum computers developed by the University of Science and Technology of China (USTC) under the leadership of Pan Jianwei and Lu Chao-Yang. Named after the ancient Chinese mathematical classic Jiuzhang Suanshu (The Nine Chapters on the Mathematical Art), the series has systematically dismantled classical computational barriers through the sophisticated manipulation of photons. Unlike the superconducting circuit models pursued by entities such as Google and IBM, the Jiuzhang architecture utilizes the intrinsic properties of light—specifically superposition, entanglement, and indistinguishably—to execute Gaussian Boson Sampling (GBS), a task designed to prove that quantum systems can outperform classical supercomputers by factors that are physically and temporally astronomical, Jiuzhang 4.0 represents the latest of series.

Global Competition and National Strategy

The competition for "quantum supremacy" is viewed as a mission-essential national asset with profound implications for the digital economy, cryptography, and national security. The Chinese government’s 15th Five-Year Plan (2026–2030) explicitly prioritizes quantum technology as a driver of economic growth. Similarly, the United States has mobilized resources through the Quantum Benchmarking Initiative and significant funding for firms like Quantinuum and PsiQuantum, which recently became the most funded quantum startup with $1 billion in investment.

Quantum Processor	Modality	Qubit/Photon Count	Key Metric/Benchmark
Jiuzhang 4.0 (2025)	Photonic	3050 Photons	10^54 speedup vs classical
Zuchongzhi 3.0 (2025)	Superconducting	105 Qubits	99.9% 1-qubit gate fidelity
Google Willow (2024)	Superconducting	105 Qubits	10^25 years simulation time
Quantinuum Helios (2025)	Trapped Ion	N/A	Most accurate commercial system
Hanyuan-1 (2025)	Neutral Atom	100 Qubits	First commercial atom-based QC

Conclusion: The Horizon of Light-Speed Computing

The Jiuzhang series has fundamentally redefined the limits of photonic quantum computing, moving from the initial 76-photon demonstration to a system of unprecedented scale and connectivity in Jiuzhang 4.0. By systematically overcoming technical barriers in light generation, interference, and detection, the USTC team has secured a globally leading position in the race for quantum computational advantage.

The current state of the technology suggests that photonic systems are no longer just laboratory prototypes but are evolving into programmable processors with the potential to transform fields as diverse as topological data analysis and molecular chemistry. As the global community moves toward the second stage of the quantum roadmap, the lessons learned from the Jiuzhang series—particularly in high-efficiency source design and spatial-temporal encoding—will be vital for the realization of the first practical quantum simulators.

While the path to a universal, fault-tolerant computer remains fraught with engineering hurdles, the staggering speedups achieved by Jiuzhang 4.0 serve as a powerful validation of the quantum-mechanical laws of superposition and entanglement. In the shifting landscape of high-performance computing, the Jiuzhang series remains the definitive benchmark for what can be achieved when the power of light is harnessed for the purpose of calculation.