Xu Yuan, Academician Yu Dabeng's team from Southern University of Science and Technology, together with Zheng Shibiao from Fuzhou University and Sun Muyan from Tsinghua University, have made breakthrough experimental progress in the field of quantum error correction based on superconducting quantum circuit system. The results were published March 23 in Nature.

The joint team extended the storage time of quantum information through the real-time repeated quantum error correction technology, exceeding the break-even point for the first time in the world, demonstrating the advantage of quantum error correction. This breakthrough is a key step towards making scalable universal quantum computing practical.

Since the error rate of quantum computer system is much higher than that of classical digital computer, quantum error correction is necessary to build a universal quantum computer with practical value, because quantum error correction can effectively protect quantum information from environmental noise interference. In the traditional quantum error correction scheme, encoding a logical qubit requires multiple redundant physical bits, which not only requires huge hardware resource overhead, but also the number of error channels will increase significantly with the increase of the number of bits, which may "correct more and more errors". Previously, there have been a number of demonstrative experimental research work on this problem, but it has not really exceeded the break-even point, that is, the effect after quantum error correction is far from the best value of the system without error correction, and can not produce positive quantum error correction gain.

To overcome the above problems, the joint research team uses infinite dimensional Hilbert space in microwave simple harmonic oscillator or bose-mode system to realize redundant encoding and quantum error correction of quantum information. In the superconducting quantum circuit system, the quantum error correction scheme based on Bose code has the advantages of simple error type, convenient error detection, good coherence performance, more efficient hardware and easy feedback control.

In this study, by developing quantum systems with high coherence performance, designing error symptom detection methods with low error rate, and improving and optimizing quantum error correction technology and other experimental means, the research team finally realized binomial coding logical qubits based on discrete variables in Bose mode, and extended the storage time of quantum information through the real-time repeated quantum error correction process. For the first time, the results exceeded the best value of the system without error correction, breaking the break-even point.

According to reports, this is the first time in the world to extend the storage time of quantum information beyond the break-even point through the active repeated error detection and error correction process, which is of landmark significance.

Related paper information:https://doi.org/10.1038/s41586-023-05784-4