Bogoliubov excitations in a Bose–Hubbard model on a hyperhoneycomb lattice

Zhou Wen-yan¹, Wu Ya-jie², Kou Su-Peng^{1, †}

(color online) (a) The energy spectra of excitations with fixed and . (b) The contour plot of the energy spectra of the third band from the bottom up of the quasiparticle-excitation modes with fixed and , the nodal loop structure is presented by the blue loop.