World Record! CSU realizes the largest 51-bit quantum entangled state!
A research team of Jianwei Pan, Xiaobo Zhu, and Chengzhi Peng at the Institute of Quantum Information and Quantum Science and Technology Innovation, Chinese Academy of Sciences, University of Science and Technology of China, in collaboration with Primrose Yuan at Peking University, has successfully realized the preparation and validation of 51 superconducting quantum bits in cluster states, which has set a new world record for the number of truly entangled bits in all quantum systems, and has realized the demonstration of a measurement-based variational quantum algorithm for the first time.
This work breaks the record of the number of true entangled bits in all quantum systems from 24 to 51, which fully demonstrates the excellent scalability of the superconducting quantum computing system, and is of great significance for the study of multi-body quantum entanglement, the realization of large-scale quantum algorithms, and measurement-based quantum computation. The relevant research results were published online on July 12 in the international academic journal Nature.
Quantum entanglement is one of the most mysterious and fundamental properties of quantum mechanics, as well as a core resource for quantum information processing and one of the fundamental sources of acceleration effects in quantum computing.
For many years, realizing large-scale multi-quantum bit entanglement has been a goal that scientists from various countries have been striving for. Since 1998, when people first realized the preparation of 3-bit GHZ states by using nuclear magnetic resonance system, the preparation of true many-body entangled states has become an important means of characterization for the scale-up of various physical systems, including photons, ion traps, NV color centers, neutral atoms and superconducting quantum bits.
Among them, superconducting quantum bits have the advantage of scale-up expansion and have developed rapidly in recent years. Scientists in China have achieved a series of important results in the preparation of superconducting quantum bits with multi-body entanglement, and have successively completed the preparation of 10-bit, 12-bit, and 18-bit true entangled states since 2017, constantly refreshing the record of the number of entangled bits in the field of superconducting quantum computing.
However, larger-scale preparation of true entangled states requires highly connected quantum systems, high-fidelity multi-bit quantum gate operations, and efficient and accurate means of characterizing the fidelity of quantum states. High connectivity ensures the possibility of large-scale quantum state generation and avoids limiting the quantum state scale due to defects and insufficient connectivity; high-fidelity quantum gates are required to connect quantum bits to form high-fidelity many-body quantum entangled states; and efficient quantum state characterization is an important guarantee for overcoming the exponential growth of the complexity of the quantum state scale with the number of bits, and for making an accurate estimation of the fidelity of the quantum state.
In physics, we call the highest degree of entanglement the true many-body entangled system - we divide a many-body system into two parts arbitrarily, no matter how to divide, there is entanglement between the two parts after the division. True many-body entanglement is the strongest form of quantum entanglement and, at the same time, is difficult to realize.
These requirements place high demands on the performance of the quantum system, its manipulation capabilities, and its means of verification, leaving the previous scale of truly entangled bits at about 20 quantum bits.
This time, based on the Zuchongzhi II superconducting quantum computing prototype constructed in the previous period, the research team further improved the fidelity of parallel multi-bit quantum gates to 99.05%, and the read accuracy to 95.09%, and combined with the large-scale quantum state fidelity verification judgment scheme proposed by the research team, successfully realized the 51-bit cluster state preparation. 51-bit cluster state preparation and verification. The fidelity of the 51-bit one-dimensional cluster state reaches 0.637±0.030, exceeding the 0.5 entanglement judgment threshold by 13 standard deviations.
History of the development of the number of bits in quantum true entangled states.
This result dramatically breaks the record of the number of true entangled bits in each quantum system from the original 24 to 51, fully demonstrating the excellent scalability of the superconducting quantum computing system.
On this basis, the research team has solved the intrinsic energy of small-scale perturbed planar codes by combining the measurement-based variational quantum intrinsic solver, and realized the measurement-based variational quantum algorithm for the first time, which lays the foundation for the measurement-based quantum computation scheme to become practical.
The line and quantum state fidelity results of 51-bit one-dimensional cluster state preparation using Zu Chongzhi II.
This work was supported by grants from the Ministry of Science and Technology, Anhui Province, Shanghai Municipality, Natural Science Foundation of China, and the Chinese Academy of Sciences.
Reference Links:
[1]https://news.ustc.edu.cn/info/1055/83980.htm
[2]https://mp.weixin.qq.com/s/aUYj5YdSATmK6AAakjn9JA
[3]https://mp.weixin.qq.com/s/rEQh1KBbxohUSLLD5B2DtA?scene=25#wechat_redirect
