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 four...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 L 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.展开更多
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA1404103,2018YFA0307200)the Key Area Research and Development Program of Guangdong Province(Grant No.2019B030330001)+1 种基金the National Natural Science Foundation of China(Grant No.12274196)Funds from Guangdong Province(Grant Nos.2019QN01X087,2019ZT08X324)。
文摘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 L 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.
