USTC Professor PAN Jianwei and his colleague CHEN Shuai, together with ZHAI Hui Group of THU, made a breakthrough in the field of ultra-cold atoms’ quantum simulation. Based on synthetic spin-orbit coupling in ultra-cold Bose gas of rubidium atoms, they successfully determined, through experiment, the phase diagram of spin-orbit coupling Bose gas at finite temperature. The result was published in the form of cover title on‘Nature Physics’ in April, which means that China is now playing an important part in research of ultra-cold atoms' quantum simulation.
Owing to strongly correlated systems caused by multiple interactions in condensed matter physics, such as high temperature superconductor and fractional quantum Hall effect, it’s hard to solving the problems directly, hampering deeper and better understanding of human beings on physics questions like these.
Simulation of ultra-cold atoms’ quantum basing on a quantum system of equivalent synthesis, through which traditional strongly correlated electron behavior of complex systems can be simulated, is considered a more direct and useful way of understanding some of the mechanisms of Condensed Matter Physics, as well as the most powerful method of solving many complicated physical systems.
Spin-orbit coupling is a key factor of many important physical phenomena, including fine structure in atoms and topological insulator discovered in recent years. Researches on spin-orbit coupling and quantum simulation can be effective ways of helping people understanding and making further utilities.
In 2011, I. Spilman group of National Institute of Standards and Technology (NIST) in U.S first synthesized the spin-orbit coupling Bose - Einstein condensate through experiments, which soon became the focus of attention and follow-up studies. Then in 2012, Zhang Jing Group of Shan Xi University, M. Zwierlein Group of MIT and Pan Jiangwei Group of USTC also made spin-obit coupling in experiments ultra-cold fermions and bosons, respectively.
Pan Jiangwei, Chen Shuai, et al synthesized spin-orbit coupling ultra-cold Bose gas of rubidium atoms through Raman coupling. With changing system temperatures, transition temperature of Bose-Einstein condensate (BEC) under the influence of spin-orbit coupling was first observed. Phase curve of BEC from magnetic plane wave phase to non-magnetic stripe phase in non-zero temperature was determined. Also, consistency between magnetic generation of Bose gases and BEC transition temperature, under the spin-obit coupling, was observed.
Their discovery helped people to better understand the basic characteristics of spin - orbit coupling Bose gases, showed a wealth of physical content of ultra-cold quantum gases under the combined effect of the interaction effects and thermodynamic effects and was a great breakthrough in ultra-cold atoms' quantum simulation, sufficiently implying a powerful function of quantum simulation.
The research got supports from CAS, the Ministry of Education, the National Natural Science Fund Committee, Ministry of Science and other major research projects.
(SONG Liang, English News Center)
