A team of Chinese scientists has developed the world’s fastest quantum computer prototype, named Jiuzhang 4.0, capable of solving complex mathematical problems in less than the blink of an eye — tasks that even for the world’s most powerful supercomputer would take longer than the age of the entire universe to crack.

The findings, published in the journal Nature on 13 May, push the quantum advantage in computing to an unprecedented level, demonstrating China’s leading position in the field.

A quantum computer operates on the laws of quantum mechanics. Its basic building blocks, called quantum bits or qubits, can exist in a superposition of both 0 and 1 simultaneously — unlike conventional bits, which are either 0 or 1.

This allows quantum computers to explore many computational paths in parallel, providing exponential speedup for certain tasks, such as solving some mathematical problems and simulating quantum systems.

Current mainstream quantum computing technological routes include superconducting, ion trap, photonic, and neutral atom systems. The Jiuzhang series, photonic quantum computers, encodes information in particles of light, and its speed depends on the ability to manipulate and control these photons.

However, in the development of large-scale photonic quantum processors, inevitable photon loss — a major source of computational error — has long been a serious constraint. As the optical network grows larger and more complex, photons can easily get “lost” in the maze, significantly degrading computational power.

To address the problem, the research team, led by the University of Science and Technology of China, developed a high-efficiency optical parametric oscillator light source and a spatiotemporally hybrid-coded interferometer, laying the groundwork for building a fault-tolerant photonic quantum processor.

They integrated 1,024 high-efficiency squeezed-state optical fields into a spatiotemporally hybrid-coded circuit with 8,176 modes, achieving a source efficiency of 92 per cent and an overall system efficiency of 51 per cent.

These represent major breakthroughs in low-loss photonic quantum information processing.

Moreover, the spatiotemporally hybrid-coded architecture allows photons to interact across both time and space dimensions, greatly improving the connectivity of the entire network while keeping the physical device scale under control.

Based on these advancements, the team achieved the manipulation and detection of up to 3,050 photons — a significant leap from the 255 photons achieved with the previous Jiuzhang 3.0, as published in 2023.

Experiments showed that the most complex data sample generated by Jiuzhang 4.0 takes only 25 microseconds to produce — where a microsecond is one-millionth of a second.

In contrast, the world’s most powerful supercomputer, El Capitan, developed by the United States, would require more than 10 to the power of 42 years to calculate the same result.

In 2020, scientists from the University of Science and Technology of China successfully developed the Jiuzhang photonic quantum computing prototype with 76 photons, making China the second country in the world to achieve the quantum computational advantage, and the first to achieve it in an optical system.

Quantum technology is emphasised in the 15th Five-Year Plan (2026-30) as both a future industry and a strategic frontier that requires sustained reinforcement.

The plan stresses the need to advance basic theories and foundational technologies while accelerating their industrial application, with goals set for the development of fault-tolerant universal quantum computers and scalable, special-purpose quantum computers.