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  • Letter
  • Open Access

Emergent orbital skyrmion lattice in a triangular atom array

Rui Cao1, Jinsen Han1, Jianmin Yuan2,1, Xiaopeng Li3,4,5,*, and Yongqiang Li1,6,†

  • 1Department of Physics, National University of Defense Technology, Changsha 410073, People's Republic of China
  • 2Department of Physics, Graduate School of China Academy of Engineering Physics, Beijing 100193, People's Republic of China
  • 3State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (MOE), and Department of Physics, Fudan University, Shanghai 200433, China
  • 4Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
  • 5Shanghai Qi Zhi Institute, AI Tower, Xuhui District, Shanghai 200232, China
  • 6Hunan Key Laboratory of Extreme Matter and Applications, National University of Defense Technology, Changsha 410073, China

  • *xiaopeng_li@fudan.edu.cn
  • †li_yq@nudt.edu.cn
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Phys. Rev. Research 5, L042042 – Published 22 December, 2023

DOI: https://doi.org/10.1103/PhysRevResearch.5.L042042

Abstract

Multiorbital optical lattices have been attracting rapidly growing research interest in the last several years, providing fascinating opportunities for orbital-based quantum simulations. Here, we consider bosonic atoms loaded in the degenerate p-orbital bands of a two-dimensional triangular optical lattice. This system is described by a multiorbital Bose-Hubbard model. We find the confined atoms in this system develop spontaneous orbital polarization, which forms a chiral Skyrmion lattice pattern in a large regime of the phase diagram. This is an orbital version of the skyrmion, reminiscent of those in spin systems. The emergence of the Skyrmion lattice is confirmed in both bosonic dynamical mean-field theory (BDMFT) and exact diagonalization (ED) calculations. By analyzing the quantum-tunneling-induced orbital-exchange interaction in the strong interaction limit, we find the Skyrmion lattice state arises due to the interplay of p-orbital symmetry and the geometric frustration of the triangular lattice. We provide experimental consequences of the orbital Skyrmion state that can be readily tested in cold atom experiments. Our study implies orbital-based quantum simulations could bring exotic scenarios unexpected from their spin analog.

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Phys. Rev. Research 5, L042042– Published 22 December, 2023
  • Received 4 December 2022
  • Revised 25 November 2023
  • Accepted 27 November 2023
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