Beating the break-even point with a discrete-variable-encoded logical qubit

Ni，Zhongchu1,2,3; Li，Sai1,2; Deng，Xiaowei1,2; Cai，Yanyan1,2; Zhang，Libo1,2; Wang，Weiting4; Yang，Zhen Biao5; Yu，Haifeng6; Yan，Fei1,2; Liu，Song1,2,7; Zou，Chang Ling8,9; Sun，Luyan4,9; Zheng，Shi Biao5; Xu，Yuan1,2,7; Yu，Dapeng1,2,3,7

2023-04-06

10.1038/s41586-023-05784-4

Nature   Impact Factor & Quartile

0028-0836

1476-4687

Quantum error correction (QEC) aims to protect logical qubits from noises by using the redundancy of a large Hilbert space, which allows errors to be detected and corrected in real time. In most QEC codes, a logical qubit is encoded in some discrete variables, for example photon numbers, so that the encoded quantum information can be unambiguously extracted after processing. Over the past decade, repetitive QEC has been demonstrated with various discrete-variable-encoded scenarios. However, extending the lifetimes of thus-encoded logical qubits beyond the best available physical qubit still remains elusive, which represents a break-even point for judging the practical usefulness of QEC. Here we demonstrate a QEC procedure in a circuit quantum electrodynamics architecture, where the logical qubit is binomially encoded in photon-number states of a microwave cavity, dispersively coupled to an auxiliary superconducting qubit. By applying a pulse featuring a tailored frequency comb to the auxiliary qubit, we can repetitively extract the error syndrome with high fidelity and perform error correction with feedback control accordingly, thereby exceeding the break-even point by about 16% lifetime enhancement. Our work illustrates the potential of hardware-efficient discrete-variable encodings for fault-tolerant quantum computation.

English

NI Journal Papers

First ; Corresponding

BIOLOGY & BIOCHEMISTRY;CLINICAL MEDICINE;MULTIDISCIPLINARY;PLANT & ANIMAL SCIENCE;ENVIRONMENT/ECOLOGY;SOCIAL SCIENCES, GENERAL;MICROBIOLOGY;ECONOMICS BUSINESS;IMMUNOLOGY;MATERIALS SCIENCE;COMPUTER SCIENCE;SPACE SCIENCE;MOLECULAR BIOLOGY & GENETICS;CHEMISTRY;NEUROSCIENCE & BEHAVIOR;PHYSICS;GEOSCIENCES;ENGINEERING

2-s2.0-85150692421

Scopus

1.Shenzhen Institute for Quantum Science and Engineering,Southern University of Science and Technology,Shenzhen,China
2.Guangdong Provincial Key Laboratory of Quantum Science and Engineering,Southern University of Science and Technology,Shenzhen,China
3.Department of Physics,Southern University of Science and Technology,Shenzhen,China
4.Center for Quantum Information,Institute for Interdisciplinary Information Sciences,Tsinghua University,Beijing,China
5.Fujian Key Laboratory of Quantum Information and Quantum Optics,College of Physics and Information Engineering,Fuzhou University,Fuzhou,China
6.Beijing Academy of Quantum Information Sciences,Beijing,China
7.International Quantum Academy,and Shenzhen Branch,Hefei National Laboratory,Shenzhen,China
8.CAS Key Laboratory of Quantum Information,University of Science and Technology of China,Hefei,China
9.Hefei National Laboratory,Hefei,China

Ni，Zhongchu,Li，Sai,Deng，Xiaowei,et al. Beating the break-even point with a discrete-variable-encoded logical qubit[J]. Nature,2023,616(7955):56-60.

Ni，Zhongchu.,Li，Sai.,Deng，Xiaowei.,Cai，Yanyan.,Zhang，Libo.,...&Yu，Dapeng.(2023).Beating the break-even point with a discrete-variable-encoded logical qubit.Nature,616(7955),56-60.

Ni，Zhongchu,et al."Beating the break-even point with a discrete-variable-encoded logical qubit".Nature 616.7955(2023):56-60.