-
本文采用虚时演化法求解拉曼光晶格的平均场Gross-Pitaevskii方程，基于其基态波函数，研究该模型中超冷原子的拓扑性质.研究发现光晶格深度和原子间相互作用强度的竞争导致了丰富的基态结构相图.当只有标量光晶格存在时，超冷原子在实空间没有涡旋产生，在动量空间表现为拓扑平庸的密度峰；当只有拉曼光晶格存在时，超冷原子在实空间出现大小相同的涡旋；当标量光晶格和拉曼光晶格共同作用时，超冷原子在实空间出现大涡旋和小涡旋，正反涡旋交错排列，在动量空间出现具有拓扑非平庸相位的衍射峰，在自旋表象中产生半量子化的斯格明子晶格.
-
关键词:
- 拉曼光晶格 /
- 超冷原子 /
- 平均场Gross-Pitaevskii方程 /
- 虚时演化法
We systematically investigate the ground-state topological properties of ultracold atoms in composite scalar–Raman optical lattices by solving the two-component Gross–Pitaevskii equation using the imaginary time evolution method. Our study focuses on the interplay between scalar and Raman optical lattice potentials and the role of interatomic interactions in shaping real-space and momentum-space structures. The competition between lattice depth and interaction strength gives rise to a rich phase diagram of ground-state configurations. In the absence of Raman coupling, atoms in scalar optical lattices exhibit topologically trivial periodic density distributions without vortex formation. When only Raman coupling is present, a regular array of equal-sized vortices emerges in one spin component, while the other remains vortex-free. Strikingly, when scalar and Raman lattices coexist, the system develops complex vortex lattices with alternating large and small vortices of opposite circulation, forming a staggered vortex configuration in real space. In momentum space, the condensate wave function displays nontrivial diffraction peaks carrying a well-defined topological phase structure, whose complexity increases with the depth of the optical potentials. As shown in Fig., in spin space, we observe the emergence of a lattice of half-quantized skyrmions (half-skyrmions), each carrying a topological charge of ±1/2. These topological textures are confirmed by calculating the spin vector field and integrating the topological charge density. Our results demonstrate how the combination of scalar and Raman optical lattices, together with tunable interactions, can induce nontrivial real-space spin textures and momentum-space topological features. These findings provide new insights into the controllable realization of topological quantum states in cold atom systems.-
Keywords:
- Raman optical lattice /
- ultracold atom /
- mean field Gross-Pitaevskii equation /
- imaginary time evolution method
-
[1] Anderson M H, Ensher J R, Matthews M R, Wieman C E, Cornell E A 1995 Science 269 198
[2] Bradley C C, Sackett C A, Tollett J J, Hulet R G 1995 Phys. Rev. Lett. 75 1687
[3] Gaubatz U, Rudecki P, Schiemann S, Bergmann K 1990 The Journal of Chemical Physics 92 5363
[4] Lin Y J, Jiménez-García K, Spielman I B 2011 Nature 471 83
[5] Aidelsburger M. 2015 Artificial gauge fields with ultracold atoms in optical lattices (New York: Springer) pp27-47
[6] Struck J, Simonet J, Sengstock K 2014 Phys. Rev. A 90 031601
[7] Xu Z F, You L, Ueda M 2013 Phys. Rev. A 87 063634
[8] Anderson B M, Spielman I B, Juzeliūnas G 2013 Phys. Rev. Lett. 111 125301
[9] Wall M L, Koller A P, Li S, Zhang X, Cooper N R, Rey A M 2016 Phys. Rev. Lett. 116 035301
[10] Liu X J, Borunda M F, Liu X, Sinova J 2009 Phys. Rev. Lett. 102 046402
[11] Wu Z, Zhang L, Sun W, Xu X T, Wang B Z, Ji S C, Deng Y J, Chen S Liu X J, Pan J W 2016 Science 354 83
[12] Wang Z Y, Cheng X C, Wang B Z, Zhang J Y, Lu Y H, Yi C R, Niu S, Deng Y J, Liu X J, Chen S, Pan J W 2021 Science 372 271
[13] Liu S, Hua W, Zhang D J 2020 Rep. Math. Phys. 86 271
[14] Han W, Zhang S Y, Jin J J Liu W M 2012 Phys. Rev. A 85 043626
[15] Han W, Juzeliūnas G, Zhang W, Liu W M 2015 Phys. Rev. A 91 013607
[16] Guo H, Wang Y J, Wang L X, Zhang X F 2008 Acta Phys. Sin. 69 010302（in Chinese） [郭慧，王雅君，王林雪，张晓斐 2020 物理学报69 010302]
[17] Kasamatsu K, Tsubota M, Ueda M 2005 Phys. Rev. A 71 043611
[18] Wu C J, Mondragon-Shem I, Zhou X F 2011, Chinese Physics Letters, 28 097102
[19] Xu Z F, Lü R, You L 2011 Phys. Rev. A 83 053602
[20] Sinha S, Nath R, Santos L 2011 Phys. Rev. Lett. 107 270401
[21] Hu H, Ramachandhran B, Pu H, Liu X J 2012 Phys. Rev. Lett. 108 010402
[22] Yang S J, Wu Q S, Zhang S N, Feng S 2008 Phys. Rev. A 77 033621
[23] Heinze S, Von Bergmann K, Menzel M, Brede J, Kubetzka A, Wiesendanger R, Blügel S 2011 Nat. Phys. 7 713
[24] Leslie L S, Hansen A, Wright K C, Deutsch B M, Bigelow N P 2009 Phys. Rev. Lett. 103 250401
[25] Ding B, Wang W H 2018 Physics 47 15 (in Chinese)[丁贝, 王文洪. 2018 物理 47 15]
[26] Nagaosa N, Tokura Y 2013 Nature Nanotechnology 8 899
[27] Fert A, Reyren N, Cros V 2017 Nature Reviews Materials 2 1
计量
- 文章访问数: 137
- PDF下载量: 6
- 被引次数: 0
下载:
