The Jiuzhang Milestone: Reflecting on China’s Photonic Quantum Leap

In the mid-2020s, as we stand on the precipice of widespread utility-scale quantum computing, it is essential to look back at the pivot points that defined our current era. While the 2019 Google Sycamore experiment provided the first spark of quantum supremacy, it was the arrival of Jiuzhang in late 2020 that fundamentally shifted the global perspective on what was possible with light-based quantum architectures.

The Photonic Revolution

Developed by the team at the University of Science and Technology of China (USTC), led by the renowned Pan Jianwei, Jiuzhang did not rely on the superconducting qubits favored by IBM or Google at the time. Instead, it utilized Gaussian Boson Sampling (GBS)—a technique using photons of light. In its initial iteration, Jiuzhang successfully detected an average of 76 photons, performing a calculation in minutes that would have taken the world’s fastest classical supercomputer of that era, the Fugaku, nearly 600 million years to complete.

Scaling Beyond the Horizon

The significance of Jiuzhang wasn't just its initial speed, but its rapid evolution. By 2021, Jiuzhang 2.0 increased the detection count, and by 2023, Jiuzhang 3.0 pushed the boundaries even further, achieving a complexity that was quintillions of times faster than classical machines. This progression demonstrated three critical things to the global community:

• Scalability: Photonic systems could be scaled without the extreme cryogenic requirements of superconducting circuits.
• Architecture Diversity: The "quantum race" was not a mono-culture; different physical realizations (photons, trapped ions, superconductors) each had unique paths to supremacy.
• Algorithmic Specialization: Jiuzhang proved that specific quantum systems could be optimized for specific mathematical problems, paving the way for the hybrid quantum-classical workflows we use today in 2026.

The 2026 Perspective

From our current vantage point in 2026, we see the fingerprints of the Jiuzhang milestone in our most advanced optical quantum networks. The breakthroughs in high-efficiency single-photon detectors and complex interferometers led directly to the robust quantum key distribution (QKD) systems now securing our global financial data. While critics in the early 2020s argued that Boson Sampling was a 'narrow' achievement, history has shown that the engineering hurdles overcome by the USTC team were the catalyst for the entire photonic industry.

As we continue to refine error correction and move toward fault-tolerant systems, the Jiuzhang series stands as a testament to the power of diversification in physics. It was the moment the world realized that the future of computing might not just be electronic—it could be fueled by light.