Hefei, Science and Technology Daily, May 22 (reporter Wu Changfeng), learned from the University of Science and Technology of China on the 22nd that the Peng Xinhua Research Group and Liu Renbao Research Group of the Chinese University of Hong Kong have proposed a theoretical scheme for selectively measuring any type of temporal correlation in open quantum multi-body systems by using quantum channels synthesized by controllable physical processes, The fourth order quantum time series correlation was successfully detected in the nuclear spin system for the first time. Relevant research results have been published online in the international academic journal Physical Review Letters.
To fully describe the dynamics of a physical system, all temporal correlation information in the system is required, that is, a set of dynamic complete temporal correlation sets. However, the current measurement scheme can only extract a few special forms of temporal correlation information. So far, there is no systematic and feasible scheme to extract all types of temporal correlation information in the dynamic complete set. How to systematically and selectively measure any quantum time series correlation with complete dynamics has always been a challenging scientific problem.
In order to solve the above problems, Peng Xinhua research group and Liu Renbao research team innovatively proposed a selective measurement protocol for any type of quantum timing correlation based on the synthesis of quantum channels by controllable physical processes. This protocol not only greatly improves the measurement signal-to-noise ratio of high-order quantum correlation and reduces the difficulty of experimental implementation, but also applies to a wider range of experimental systems, including single spin and ensemble quantum systems. Using high-precision quantum control of nuclear magnetic resonance, the feasibility of the measurement protocol was verified experimentally by researchers on a multi spin system, and the fourth order quantum time series correlation in a quantum multi body system was successfully measured for the first time. Next, the researchers applied the high-order quantum correlation information obtained from the experiment to the high-precision quantum optimization control task. When the fourth order quantum correlation correction is considered in the optimal control, the fidelity of the quantum gate can be improved from 99.987% to 99.99996%.
The researchers said that this research has potential application value in the field of quantum information and quantum multi-body physics, such as quantum control and quantum precision measurement, and further improving the signal-to-noise ratio and spectral resolution of measuring quantum time series correlation. The reviewers spoke highly of this work: "This is an important supplement in the field of quantum measurement, and provides insight into quantum system dynamics."
