Entanglement by Superconducting Qubits Approaches Heisenberg Limit


Recently, scientists from Institute of Physics, Chinese Academy of Sciences and Beijing Academy of Quantum Information Sciences have created non-Gaussian entanglement with 10 and 19 superconducting qubits. The prepared entanglement can be used for quantum metrology with precision close to the Heisenberg limit. In the experiments, the researchers have successfully obtained the non-linear squeezed parameters to characterize the non-Gaussian entangled states, which is the first time obtained experimentally. The results indicate that the obtained phase sensitivity based on quantum Fisher information for multi-qubit entanglement is the best one for similar number of qubits. The results have been published in  Physical Review Letters in April 12, 2022 with title: Metrological Characterization of Non-Gaussian Entangled States of Superconducting Qubits.       

It is expected that superconducting quantum computation is promising for practical applications based on its remarkable properties of scalability, high precision in control and efficiency for realizing quantum circuits. Researchers in IBM focus on cloud quantum computation and have attracted much attention.

The results presented above are obtained by Cloud Quantum Computation group of Beijing Academy of Quantum Information Sciences. They have made a series of achievements in superconducting quantum computation including works about quantum simulation of many-body systems and generation of multiparticle entanglement. This work was supported by National Natural Science Foundation of China, and Chinese Academy of Sciences and Beijing Natural Science Foundation.


Figure 1. In the experiments, 10 and 19 superconducting qubits are used. Their couplings are presented above. The sequences of operation in the experiment to obtain quantum Fisher information are given.



Figure 2. Comparison of standard squeezing parameter and non-linear squeezing parameter for 10 qubits are given.


Figure 3, Quantum circuits to prepare the entangled states and the readout.

Reference: Kai Xu, Yu-Ran Zhang, Zheng-Hang Sun, Hekang Li, Pengtao Song, Zhongcheng Xiang, Kaixuan Huang, Hao Li, Yun-Hao Shi, Chi-Tong Chen, Xiaohui Song, Dongning Zheng, Franco Nori, H. Wang, and Heng Fan. 2022. "Metrological Characterization of Non-Gaussian Entangled States of Superconducting Qubits." Phys. Rev. Lett. 128, 150501.