News from the University of Science and Technology in China shows that the University of Science and Technology in China, Pan Jianwei, Chen Shuai, and Liu Xiongjun at Peking University have recently made significant progress in the topological quantum of super-cold atom simulation. Materials. The research team used the ultra-cold atom system to make the world’s first three-dimensional spin-orbit coupling a reality, and developed a suitable sun semi-metal band structure with only one foreign point.

Ultra-Cold Atom Spin-Orbit Coupling Research, in collaboration with Peking University, University of Science and Technology, China However, there are two technical difficulties in testing this project:

How to extend the two dimensional Raman coupling to the three dimensional structure?

How can traditional two-dimensional imaging be used to detect tri-dimensional momentum space?

In response to these two major technical problems, the research team designed an efficient optical path. Optical lattice 45 by precisely constructing the Raman possibilities of the three-dimensional structure of the theoretical project by rotating and locking, integrating three-dimensional spin-orbit coupling; At the same time; The band structure with only two sun points is synchronized by adjusting the experimental parameters.

Figure 1: A, Schematic diagram of a three-dimensional spin-orbit coupling device. B. The experimentally constructed three-dimensional Raman potential structure causes spin flipping and tunneling of atoms between lattice points.

In the case of the findings, the research team used a virtual tomography method proposed jointly by Peking University Group and G-B Joe of Hong Kong Science and Technology and applied it to the current three-dimensional optical lattice system. . Using the symmetry of the system, Raman adjusts the separation equivalence to obtain spin textures on different momentum planes in the z-direction, and then reconstructs the spin textures in the three-dimensional momentum space to find the sun point; Quantum calibration dynamics are used to extract the spin texture, obtain the topological characteristics of the aircraft’s energy band, and then determine the position of the veil point. Both methods confirm each other, which confirms the realization of the ideal sun semi-metal energy band.

Figure 2: A, Reconstruct the three-dimensional spin texture using virtual tomography to locate the two wire points. B, Calibrates the position of the foreign point by quantum calibration dynamics.

In addition, based on this work, the research team will explore more specific phenomena and physical processes in Weil’s semimetals; It can also extend its technological solutions to Fermien systems to conduct research on strongly correlated topological physics.

The results of the research were recently published in the international academic journal “Science”. Relevant critics highly praise their achievements:

We open a new direction for the cold atom system to study new phenomena in Veil physics;

As the first recognition of three-dimensional spin-orbit coupling in a cold atom system, this is a major breakthrough in the field, and provides a new tool for cold atom research;

We have a very valuable result in identifying the ideal sun point, which gives complementary research direction to solid systems.

This research work is supported by the Ministry of Science and Technology, National Natural Science Foundation Foundation of China, Chinese Academy of Sciences,EducationMinistry, Anhui Province, Shanghai.

Paper link:https://science.sciencemag.org/content/372/6539/271