Scientists first realized highly sensitive microwave sensing based on the critical enhancement of Rydberg atoms. Hefei, October 18 (Reporter Ding Yiming, Correspondent Wang Min) Recently, the team of academicians Guo Guangcan from the University of Science and Technology of China made new progress in precision measurement based on phase transition. Team Professor Shi Baosen, Professor Ding Dongsheng and Klaus M? Of Aarhus University, Denmark? Professor lmer and Professor Charles S. Adams of Durham University in the United Kingdom cooperated to improve the precision and sensitivity of the measurement of the microwave electric field of the Rydberg atom by using the phase transition of the strong correlation system, and the sensitivity can reach 49 nanovolts per centimeter per root hertz. Relevant research results were published in Nature Physics on October 17. The development of modern advanced quantum measurement system is of great research significance. It is not only a major national demand, but also in line with the international development trend. Because of its large electric dipole moment and strong response to weak electric field, the Rydberg atom has become a very promising quantum system for microwave measurement. In addition, due to the long-range strong interaction between Rydberg atoms, it is often used to simulate strong correlation systems and phase transitions. Strong correlation systems are more sensitive to external disturbances near the critical point, and can be used in the field of quantum precision measurement. Although there are a lot of theoretical reports on the use of the critical state of strongly correlated systems for quantum sensing, it has not been successfully realized in experiments. "The main reasons are that it is difficult to prepare the phase transition process of the multi-body system, and the field control technology of the critical point is lacking." Professor Ding Dongsheng, co author of the paper and key laboratory of quantum information, Chinese Academy of Sciences, introduced the paper. In recent years, the scientific research teams of Shi Baosen and Ding Dongsheng have made important progress in focusing on the scientific research of quantum simulation and quantum precision measurement by using the Rydberg atomic system. In this work, the team developed the coupling technology between the Rydberg atomic critical point and the microwave electric field. Based on room temperature rubidium atomic system, the precision and sensitivity of microwave measurement are significantly improved by using the characteristic that the phase transition point of multi-body system is more sensitive to microwave disturbance. Ding Dongsheng said: "The experiment shows that the atomic transmission spectrum line in the multi-body system becomes steeper near the phase transition point, which is equivalent to a ruler with finer scale in the frequency domain, so it has higher accuracy for microwave measurement." When evaluating sensors, a key quantity is Fisher information, which indicates how much information a measurement contains about unknown parameters. The experiment shows that the Fisher information of the multi-body system at the critical point is significantly improved by three orders of magnitude compared with the case of few body without phase transition. Corresponds to the improvement of measurement accuracy by at least one order of magnitude, and increases with the increase of measurement time, showing an exponential growth trend. This work was highly praised by the reviewers: "This experiment is truly groundbreaking and has significant potential impact, because it opens the door to the development of a new generation of quantum sensors based on strong interaction multi-body systems." "The impressive sensitivity of 49 nanovolts per centimeter per square hertz is a good indication of the potential application of this method in metrology." (Outlook New Times)