Realization of $^{87}$Rb Bose–Einstein Condensates in Higher Bands of a Hexagonal Boron-Nitride Optical Lattice
Jin-Yu Liu1,2 , Xiao-Qiong Wang3* , and Zhi-Fang Xu2,3*
1 Department of Physics, Harbin Institute of Technology, Harbin 150001, China2 Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China3 Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
Abstract ：Ultracold neutral atoms in higher bands of an optical lattice provide a natural avenue to emulate orbital physics in solid state materials. Here, we report the realization of $^{87}$Rb Bose–Einstein condensates in the fourth and seventh Bloch bands of a hexagonal boron-nitride optical lattice, exhibiting remarkably long coherence time through active cooling. Using band mapping spectroscopy, we observe that atoms condensed at the energy minimum of $\varGamma$ point ($K_{1}$ and $K_{2}$ points) in the fourth (seventh) band as sharp Bragg peaks. The lifetime for the condensate in the fourth (seventh) band is about 57.6 (4.8) ms, and the phase coherence of atoms in the fourth band persists for a long time larger than 110 ms. Our work thus offers great promise for studying unconventional bosonic superfluidity of neutral atoms in higher bands of optical lattices.
收稿日期: 2023-04-18
Editors' Suggestion
出版日期: 2023-07-21
PACS:
67.85.-d
(Ultracold gases, trapped gases)
37.10.Jk
(Atoms in optical lattices)
03.75.Lm
(Tunneling, Josephson effect, Bose-Einstein condensates in periodic potentials, solitons, vortices, and topological excitations)
67.85.De
(Dynamic properties of condensates; excitations, and superfluid flow)
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2023, Vol. 40 
