China University of Science and Technology achieves single-ion super-resolution imaging
The team of academician Guo Guangcan of our school has made important progress in the research of cold atom super-resolution imaging. The team Li Chuanfeng, Huang Yunfeng, Cui Jinming and others achieved super-resolution imaging of a single ion in the ion trap system. The results were published in the internationally renowned journal "Physics Review Letters" on December 23.
The cold atom system, including ions trapped in ion traps and atoms trapped in light fields, is an ideal experimental platform for studying quantum physics, as well as an important physical system for experimental research on quantum simulation, quantum computing, and quantum precision measurement. One of the core experimental techniques in the cold atom system is high-resolution single-particle imaging. In the past ten years, the microscopic imaging technology of the cold atom system has developed rapidly, and advanced technologies such as quantum gas microscope, optical tweezers atomic array, and high-resolution trapped ion imaging have emerged. However, these technologies are still limited by the basic optical diffraction limit, and the resolution can only reach the order of optical wavelength. It is difficult to study quantum phenomena related to the details of the wave function. The study of such problems requires optical super-resolution imaging.
As we all know, optical super-resolution imaging has developed into a mature tool in the fields of chemistry and biology, which led to the 2014 Nobel Prize in Chemistry. However, due to the complexity of cold atom experiments, it is extremely challenging to apply super-resolution imaging technology to cold atom systems. Prior to this, the direct super-resolution imaging of single atoms (ions) in the world has not yet made progress.
In this experiment, the research team borrowed from the stimulated depletion super-resolution imaging method (STED) in the classical imaging field, combined with the atomic quantum state initialization and reading technology of the cold atom system, and realized for the first time a single cold atom (ion ) Super-resolution imaging. Experimental results show that the spatial resolution of the imaging method can exceed the diffraction limit by more than one order, and the imaging resolution of 175 nm can be achieved by using an objective lens with a numerical aperture of only 0.1. In order to further demonstrate the time resolution advantage of this method, the research team achieved both a time resolution of 50 ns and a single ion positioning accuracy of 10 nm, and used this method to clearly capture the rapid and simple harmonic oscillations of trapped ions in the ion trap. . Theoretically, by increasing the numerical aperture of the imaging objective and the center extinction ratio of the depleted light (the doughnut spot), the spatial resolution can be further improved to below 10 nm.
Figure 1 Single-ion super-resolution imaging. (A) Single ion fluorescence imaging, (b) Depleted light mode using ion as probe measurement, (c) Single ion super-resolution imaging result, (de) Relationship between imaging resolution and depleted light intensity and depletion time , (F) Single ion fluorescence imaging (FM) and super-resolution imaging (GSD) resolution comparison.
Figure 2 The super-resolution imaging method is applied to ion dynamics measurement. (A) Using electrical signals to excite the simple harmonic motion of the ions in the y direction, (b) imaging timing, (c) imaging the moving ions at different times, fitting the center of the image spot (blue cross) to clearly observe the simple harmonic in the y direction vibration. (D) Ion trajectories with different excitation voltages.
This experimental technique can be extended to the multi-body and correlation measurement of cold atom systems, and it has good compatibility with other cold atom systems. It can be applied to optical lattices, neutral atom optical tweezers, and cold atom-ion hybrid systems. Wait. The reviewers spoke highly of the work: "It clearly shows an important step towards the direct dynamic measurement of single-atom quantum states of motion, and has application prospects in multi-body entangled systems"; "The proposal and implementation of this work fills in The previously missing important tool for precise measurement of the position of atoms has the potential to achieve spatial resolution of single motion quantum of high-frequency motion."
The co-first authors of the paper are Dr. Zhonghua Qian and associate researcher Cui Jinming of the Key Laboratory of Quantum Information of the Chinese Academy of Sciences. The research was funded by the Ministry of Science and Technology, the National Natural Science Foundation of China, the Chinese Academy of Sciences and Anhui Province.
Paper link:https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.263603
