CHINA’S superconducting quantum computing prototype Zuchongzhi 3.2 has achieved a key breakthrough by demonstrating quantum error correction below the fault-tolerance threshold on a surface code with a code distance of seven, the Science and Technology Daily reported.

This breakthrough confirms that logical error rates decrease significantly as code distance increases, marking a crucial milestone in achieving scalable quantum error correction where performance improves after crossing the threshold. It also pioneers a more efficient “all-microwave control” pathway, distinct from methods used by companies like Google, laying vital technical groundwork for large-scale fault-tolerant quantum computing.

The research, conducted by a team from the University of Science and Technology of China (USTC) including Pan Jianwei, Zhu Xiaobo, Peng Chengzhi, and associate professor Chen Fusheng, was published as a cover paper and an Editors’ Suggestion in Physical Review Letters on Monday.

Achieving system control precision beyond the strict error-correction threshold is widely considered the critical line separating laboratory prototypes from practical quantum computing systems. Building on prior work, the team proposed and implemented a novel “all-microwave quantum state leakage suppression architecture” on the 107-qubit Zuchongzhi 3.2 processor. Using this architecture, they realized a surface-code logical qubit with a code distance of seven.

Experimental results showed a significant reduction in logical error rate as code distance increased, with an error-suppression factor reaching 1.4. This confirms the system operates below the error-correction threshold and has achieved increasingly effective error correction.

Quantum computing is recognized as a pivotal technology for the next-generation information revolution. In March, the same USTC team led by Pan successfully built the 105-qubit Zuchongzhi 3.0 prototype, which again broke the world record for quantum computational advantage in a superconducting system, according to Xinhua.(SD-Agencies)