Spectra and dynamics of three-dimensional lattice quantum droplets in Lee–Huang–Yang fluid

The spectral properties and dynamical behaviors of three-dimensional quantum droplets loaded in an optical lattice within a Lee–Huang–Yang fluid are investigated. Using a beyond-mean-field model combined with variational analysis and numerical simulations, we explore the system's ground states and dynamics. Our results demonstrate that lattice anisotropy and quantum fluctuations effectively tune the excitation spectrum and lift the degeneracy of the breathing modes. Through Floquet dynamics, we identify distinct nonlinear features, including higher-order harmonics and frequency-mixing modes. Quench dynamics studies show center-of-mass oscillations characterized by a linear frequency and an additional nonlinear frequency. Additionally, we find that the collision dynamics of droplet pairs strongly depend on their relative phase, resulting in diverse dynamical behaviors. These findings provide valuable insights for understanding and manipulating quantum droplets in optical lattices, offering some reference for exploring quantum fluctuations in periodically confined geometries.