Quantum phases of $sp^2$-orbital bosonic gases in a hexagonal lattice

Pengfei Zhang; Hui Tan; Jianmin Yuan; Yongqiang Li

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arXiv · 2305.07162

Quantum phases of $sp^2$-orbital bosonic gases in a hexagonal lattice

Pengfei Zhang·Hui Tan·Jianmin Yuan·Yongqiang Li

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Abstract

Orbital degree of freedom plays an important role for understanding quantum many-body phenomena. In this work, we study an experimentally related setup with ultracold bosons loaded into hybridized bands of two-dimensional hexagonal optical lattices. We find that the system supports various quantum many-body phases at zero temperature, including chiral superfluid and chiral Mott insulator by breaking time-reversal symmetry, and time-reversal-even insulating phase, based on dynamical mean-field theory. To explain the time-reversal-even phase, a fourth-order orbital-exchange model is derived to explain the underlying mechanics. To relate to experimental situations, we make band-structure calculations to obtain the Hubbard parameters, and show that these orbital ordering phases persist also in the presence of next-nearest-neighbor hopping.

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Pengfei Zhang, Hui Tan, Jianmin Yuan, Yongqiang Li. 2023-05-11. Quantum phases of $sp^2$-orbital bosonic gases in a hexagonal lattice. https://arxiv.org/abs/2305.07162

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