Superfluid-Mott-Insulator Transition in an Optical Lattice with Adjustable Ensemble-Averaged Filling Factors  

作　　者：Shifeng Yang Tianwei Zhou Chen Li Kaixiang Yang Yueyang Zhai Xuguang Yue Xuzong Chen 杨仕锋;周天伟;李辰;杨凯翔;翟跃阳;乐旭广;陈徐宗(School of Electronics Engineering and Computer Science,Peking University,Beijing 100871;Vienna Center for Quantum Science and Technology,Atominstitut,TU-Wien,Stadionallee 2,1020 Vienna,Austria;Innovative Research Institute of Frontier Science and Technology,Beihang University,Beijing 100191;Wuhan National Laboratory for Optoelectronics(WNLO),Wuhan 430074)

机构地区：[1]School of Electronics Engineering and Computer Science,Peking University,Beijing 100871 [2]Vienna Center for Quantum Science and Technology,Atominstitut,TU-Wien,Stadionallee 2,1020 Vienna,Austria [3]Innovative Research Institute of Frontier Science and Technology,Beihang University,Beijing 100191 [4]Wuhan National Laboratory for Optoelectronics(WNLO),Wuhan 430074

出　　处：《Chinese Physics Letters》2020年第4期5-8,共4页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(Grant Nos.61703025,91736208,1150432&and 11920101004);the National Program on Key Basic Research Project of China(Grant Nos.2016YFA0301501 and 2017YFA0304204).

摘　　要：We study the quantum phase transition from a superfluid to a Mott insulator of ultracold atoms in a threedimensional optical lattice with adjustable filling factors.Based on the density-adjustable Bose-Einstein condensate we prepared,the excitation spectrum in the superfluid and the Mott insulator regime is measured with different ensemble-averaged filling factors.We show that for the superfluid phase,the center of the excitation spectrum is positively correlated with the ensemble-averaged filling factor,indicating a higher sound speed of the system.For the Mott insulator phase,the discrete feature of the excitation spectrum becomes less pronounced as the ensemble-averaged filling factor increases,implying that it is harder for the system to enter the Mott insulator regime with higher filling factors.The ability to manipulate the filling factor affords further potential in performing quantum simulation with cold atoms trapped in optical lattices.

关 键 词：EXCITATION SPECTRUM quantum 

分 类 号：O469[理学—凝聚态物理]