China’s “Jiuzhang” Quantum Computer Achieves Breakthrough in Quantum Supremacy

In December 2020, researchers led by Pan Jianwei at the University of Science and Technology of China published a paper in *Science* announcing the successful construction of a 76‑photon quantum computer named “Jiuzhang.” The device performed Gaussian boson sampling in just 200 seconds, a task that would take the world’s fastest supercomputer millions of years.

Quantum information combines quantum mechanics with information science, leveraging phenomena such as superposition, entanglement, and measurement. Unlike classical bits, quantum bits (qubits) can represent infinitely many states, offering exponential computational advantages for certain problems, though practical algorithms remain limited.

Jiuzhang’s performance surpasses Google’s 53‑qubit “Sycamore” processor by orders of magnitude: it is a million‑times faster than the top classical supercomputer “Fugaku” for the same sampling task and a hundred‑times faster than Sycamore, while also avoiding the sample‑size dependence that challenged Google’s claim of quantum supremacy.

Despite this milestone, quantum computers are still far from replacing classical machines. Experts outline three stages: achieving quantum supremacy on specialized problems, building dedicated quantum simulators for materials science and high‑temperature superconductivity, and finally developing fault‑tolerant, programmable universal quantum computers requiring millions of physical qubits.

China is simultaneously advancing quantum communication infrastructure, including a 35,000‑km national quantum backbone, regional “Qi‑lu” lines, and satellite‑based quantum networks, as well as constructing a national quantum information science laboratory with investments exceeding tens of billions of yuan.

The article concludes that while quantum computers will initially complement rather than replace classical computers, ongoing national projects and international research are rapidly pushing the field toward practical, large‑scale quantum technologies.