To lay the foundation for the practical application of quantum computing, Chinese scientists have broken the world record for the number of truly entangled bits in quantum systems
Recently, the research team composed of Pan Jianwei, Zhu Xiaobo, Peng Chengzhi, etc. from the Institute of Quantum Information and Quantum Technology Innovation of the Chinese Academy of Sciences, University of Science and Technology of China, cooperated with Yuan Xiao, Peking University, successfully realized the preparation and verification of 51 superconducting quantum bit clusters, broke the world record for the number of true entangled bits in all quantum systems, and demonstrated the measurement based variational quantum algorithm for the first time. This work significantly increases the number of truly entangled bits in quantum systems from 24 to 51, fully demonstrating the excellent scalability of superconducting quantum computing systems. It is of great significance for studying multi body quantum entanglement, implementing large-scale quantum algorithms, and measurement based quantum computing. The relevant research results were published online on July 12th in the international academic journal Nature.
Quantum entanglement is one of the most mysterious and fundamental properties in quantum mechanics, as well as a core resource for quantum information processing and a fundamental source of acceleration effects in quantum computing. For many years, achieving large-scale multi qubit entanglement has been a goal pursued by scientists from various countries. Chinese scientists have achieved a series of important results in the preparation of multi body entanglement in superconducting quantum bits. Since 2017, they have successively completed the preparation of 10 bit, 12 bit, and 18 bit true entangled states, continuously breaking the record for the number of entangled bits in the field of superconducting quantum computing.
However, larger scale preparation of true entangled states requires high connectivity quantum systems, high fidelity multi bit quantum gates, and efficient and accurate characterization methods for quantum state fidelity. Due to the difficulty in meeting the requirements for quantum system performance, manipulation capability, and verification methods, the scale of true entangled bits has not exceeded 24 quantum bits.
On the basis of the "Zuchong-2" superconducting quantum computing prototype built by the research team in the early stage, the fidelity of parallel multi bit quantum gates was further improved to 99.05%, and the reading accuracy was improved to 95.09%. Combined with the large-scale modulus sub state fidelity verification scheme proposed by the research team, 51 bit cluster state preparation and verification were successfully achieved. On this basis, the research team has for the first time implemented a measurement based variational quantum algorithm, laying the foundation for the practical application of measurement based quantum computing solutions.