内容摘要：The coherent nonlinear interactions between collective excitations, such as magnons and phonons, drive emergent phenomena in quantum materials, yet capturing their dynamics in real time remains a formidable challenge. In this talk, we demonstrate how terahertz 2D coherent spectroscopy can directly resolve these hidden interactions in the van der Waals antiferromagnet FePS3. By mapping out 2D coherent spectra, we isolate both second- and third-order nonlinear responses of antiferromagnetic magnons, providing definitive evidence of sum- and difference-frequency generation between magnons and lattice vibrations. Finally, we will discuss the symmetry requirements for nonlinear magnonic processes and explore how exploiting these coherent nonlinearities allows us to entangle magnetic and vibrational degrees of freedom, opening new pathways for ultrafast quantum control and hybrid terahertz technologies.