Interaction-induced spectral transfer in temporally perturbed binary quantum droplets

Abstract

We investigate interaction-mediated spectral transfer in a driven one-dimensional binary Bose–Einstein condensate beyond mean-field interactions. The system is modeled using the extended Gross–Pitaevskii equation incorporating beyond-mean-field fluctuations through the Lee–Huang–Yang correction and confined within a harmonic potential supplemented by a localized Gaussian spike with tunable interactions. Using a variational approach, we analyze the temporal evolution of droplet widths, their spectral response, and the associated phase-space dynamics when periodic perturbations are applied to only one condensate component. Temporal modulation of the trap strength, spike amplitude, and nonlinear interaction induces pronounced nonlinear dynamics characterized by higher harmonics and mixed-frequency spectra. Remarkably, these spectral signatures are simultaneously generated in the initially unperturbed component through intercomponent coupling, revealing a robust mechanism of interaction-mediated spectral transfer and nonlinear frequency mixing. Complementary analysis based on the Wigner phase-space distribution further uncovers coherent intercomponent dynamics and internal collective modes that do not trivially follow the real-space oscillations of the droplet widths. These results highlight the role of coupling-induced nonlinearities in driven multicomponent quantum fluids and establish binary quantum droplets as a controllable platform for nonlinear spectral engineering.