A research investigating a novel behavior in manybody quantum phase transition was published

Experimental setup and improved band-mapping method

Non-equillium physics and dynamical behavior has been widely discussed these days, especially with the extension of quantum phase transition. Kibble Zurek mechanism is a commonly used approach to investigate the dynamical behavior near phase transition point, based on the spontaneous symmetry breaking theory. But beyond thermodynamical phase transition, where topological phase transition happens without symmetry breaking, a question naturally emerges: can KZ mechanism also describe quantum phase transition, or is there any novel phenomenon beyond this?

Cooperating with Prof. Xuzong Chen and Prof. Xiaoji Zhou in Peking University, Prof. Jiazhong Hu and Prof. Wenlan Chen investigated the novel dynamical behavior near the Superfluid-Mott insulator phase transition point. By band mapping method in optical lattice, we find the dynamical phase transition index has two different values if we observe the relaxation time and topological defect excitation independently. When the manybody system ramps to a symmetry conserved state from a symmetry breaking state, the energy gap opens by a 1/2 index initially and 1 index afterwards, so we can get two index values due to the competion of two different ways of energy gap opening. This work verifies the importance of energy gap opening in quantum phase transition, paving the way to further study of quantum phase transition dynamics.

Our research assistant Ruixiao Yao( a Phd student in MIT now) is the second auther, Phd student Shuai Wang also participated the experiment. This work is published on < Physical Review Letters > recently.

Click the link to read more about our work: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.200601

Also see report in the department of Physics, Tsinghua University: https://mp.weixin.qq.com/s/223WUJh-uotrf8bBohZImg