MATHEMATICAL SCIENCES

For the first time, the field of quantum error correction has surpassed the break-even point


On March 22, Xu Yuan’s research group, academician of the Chinese Academy of Sciences and Yu Dapeng’s team of Southern University of Science and Technology, together with Zheng Shibiao of Fuzhou University and Sun Luyan of Tsinghua University, made breakthroughs in the field of quantum error correction based on superconducting quantum circuit systems, and the latest research results were published in Nature.

Research diagram Photo courtesy of the research team

Through real-time repeated quantum error correction technology, the joint team extended the storage time of quantum information, surpassing the break-even point for the first time in the world, and demonstrating the advantages of quantum error correction. This milestone breakthrough represents a key step towards practical scalable universal quantum computing.

In recent years, although the research in the field of quantum information processing based on superconducting quantum circuit systems has made rapid progress, because the error rate of quantum computer systems is much higher than that of classical digital computers, quantum error correction is essential to build a general-purpose quantum computer with practical value, because quantum error correction can effectively protect quantum information from interference by noise in the environment.

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 increases significantly with the increase of the number of bits, which may present an embarrassing situation of “more correction and more error”. Although this quantum error correction scheme has had a number of demonstration experimental research work, it still cannot solve the problem of “more correction and more error” in the process of quantum error correction, and does not really exceed the break-even point, that is, the effect after quantum error correction is far from reaching the best value in the case of no error correction in the system, and cannot really produce positive quantum error correction gain. This is also the core bottleneck of the current quantum error correction technology that cannot be practical and scalable.

In order to overcome the above problems, the joint research team uses the infinite-dimensional Hilbert space in microwave simple harmonic oscillators or boson mode systems to realize redundant coding and quantum error correction of quantum information. In the superconducting quantum circuit system, the quantum error correction scheme based on boson coding has the advantages of simple error type, convenient error detection, good coherent performance, more efficient hardware, and easy implementation of feedback control. In this study, the research team finally realized the logical qubit based on binomial coding of discrete variables in Bose mode by developing a quantum system with high coherent performance, designing and implementing an error symptom detection method with low error rate, and improving and optimizing quantum error correction technology, and extended the storage time of quantum information through the real-time repeated quantum error correction process, and the relevant results exceeded the best value in the system without error correction for the first time, that is, the break-even point was broken.

According to reports, this is also 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 milestone significance. (Source: China Science News, Diao Wenhui)

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



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