Chinese quantum breakthrough leaves world’s fastest supercomputer behind

In less time than a human blink, a new Chinese quantum computer prototype called Jiuzhang 4.0 can crack mathematical problems so complex that the world's most powerful supercomputer would need longer than the universe's entire lifespan to compute them. The breakthrough, published Wednesday in the journal Nature, marks a new peak in quantum computational advantage and cements China's leading role in the field.

Unlike conventional computers that process bits as either 0 or 1, quantum machines use qubits that can exist in both states at once. This superposition allows them to explore countless computational paths simultaneously, offering exponential speed gains for tasks like solving certain math problems or simulating quantum systems.

The Jiuzhang series belongs to the photonic route of quantum computing, encoding data in light particles. Its performance hinges on how precisely scientists can manipulate and control those photons. But a persistent obstacle has been photon loss — as optical networks grow larger, photons get "lost" in the maze, introducing errors that degrade computing power.

To overcome this, the team from the University of Science and Technology of China built a high-efficiency optical parametric oscillator light source and a spatiotemporally hybrid-coded interferometer. These innovations lay the foundation for a fault-tolerant photonic quantum processor. The researchers integrated 1,024 high-efficiency squeezed-state optical fields into a circuit with 8,176 modes, achieving a source efficiency of 92 percent and an overall system efficiency of 51 percent — major advances in low-loss photonic quantum information processing.

The spatiotemporally hybrid-coded architecture lets photons interact across both time and space, boosting network connectivity while keeping the physical device size manageable. Based on these improvements, the team manipulated and detected up to 3,050 photons — a dramatic jump from the 255 photons achieved with Jiuzhang 3.0 in 2023.

Experiments showed that Jiuzhang 4.0 generates its most complex data sample in just 25 microseconds. By contrast, El Capitan, the world's most powerful supercomputer built by the United States, would need more than 10 to the power of 42 years to calculate the same result.

China first achieved quantum computational advantage in 2020 with the original Jiuzhang prototype, which used 76 photons and made the country the second in the world to reach that milestone — and the first to do so in an optical system.

Quantum technology is highlighted in China's 15th Five-Year Plan (2026-30) as both a future industry and a strategic frontier requiring sustained reinforcement. The plan calls for advancing basic theories and foundational technologies while speeding up industrial applications, with targets set for developing fault-tolerant universal quantum computers and scalable, special-purpose quantum machines.