On May 17th, Prof. Dajun Wang from the Chinese University of Hong Kong (CUHK), had delivered a lecture entitled "Experiments with an ultracold Rb and Na mixture".
Heteronuclear ultracold atomic mixtures has always been a frontier topic, in the research of cold atomic physics. By combining techniques like laser cooling, evaporative cooling and sympathetic cooling, heteronuclear atomic gases can be brought into the regime of quantum degeneracy. Furthermore, optical lattices and Feshbach resonances can be used to tune the external confining and inter-atomic interactions, through which exotic phenomena such as superfluidity and ultracold molecules can be investigated in a controllable way. Therefore, many research teams worldwide , including W. Ketterle at MIT and Jun Ye at JILA, are devoted into this direction, of which the CUHK team led by Prof, Wang is a new and fast growing competitor.
In this lecture, Prof, Wang first made some comments on the prospects of ultracold heteronuclear mixtures in the research of quantum simulation and ultracold molecules. and briefly summarized the characters and current states of various experimental systems. Then he thoroughly illustrated the reason and advantages of choosing Rubidium(Rb) and Sodium(Na) mixture for his team. Particularly he emphasized since the heternuclear Feshbach resonances are distant from the corresponding homonuclear Feshbach resonances in this system, it is more suitable for preparing ultracold polar molecules, which constitutes one of their focus, After that, Prof,. Wang demonstrated their experimental apparatus. They used a optically plugged quadrupole magnetic trap in obtaining Rubidium BEC, followed by a non-perpendicular crossed beam optical dipole trap for the sympathetic cooling of Sodium., finally they reached quantum degeneracy in this heteronuclear mixture. Based on this apparatus and theoretical results from their collaborators, they made a deeply investigation into the positions and properties of various Feshbach resonances in this mixture. At the end of this lecture, Prof. Wang gave a outlook into the possible directions in obtaining ultracold polar molecules and molecular quantum degeneracy..
The lecture had attracted experts and students both in experimental and theoretical research, and Prof. Wang carried out productive communication and discussion with research staff and students .
Prof. Dajun Wang obtained his master degree from Peking University in 2003 and doctoral degree from the University of Connecticut in 2007, respectively. During year 2007 to 2010, he carried out postdoctoral research ar the University of Colorado and JILA. Since 2010, he has been an assistant professor at the Chinese University of Hong Kong. There, he leads his team into the research of ultracold atomic and molecular physics.