In condensed matter systems, astronomical numbers of electrons and nuclei are organized to form complex, hierarchical structures composed of subsystems with distinct lattice, spin, orbital, and charge degrees of freedom. When these subsystems are excited, their cooperative, wave-like motions give rise to collective excitations, such as lattice vibrations (phonons), spin precessions (magnons), and electronic excitations (excitons). These collective modes span a wide range of energy and time scales, signifying the emergence of collective phases and orders. Thus, the dynamic behavior of these collective modes provides valuable insights into the nature of quantum phases and their transformations. Furthermore, the interactions between different collective modes open up possibilities for generating new material functionalities that are inaccessible in thermal equilibrium.

Precisely controlled laser pulses can activate nonlinear light-matter interactions of quantum materials. A key feature of this approach is that the systems investigated are no longer confined to their ground state and may exhibit behaviors that diverge significantly from those observed in thermodynamic equilibrium. These systems can be driven into the nonlinear regime with self-anharmonicity and couplings between distinct collective modes, switched into metastable states hidden in conventional phase diagrams, or manipulated by atomically strong light fields to exhibit novel functionalities. Increasing evidence suggests that these non-equilibrium dynamics not only provide insight into the equilibrium properties of materials but also reveal new physics that may be overlooked otherwise.

Scientific discoveries are frequently propelled by the development of new experimental tools, which enable us to explore uncharted territories and investigate once-inaccessible phenomena. Driven by fundamental scientific challenges, I develop innovative spectroscopic and imaging techniques to enhance our ability to measure, visualize, and manipulate quantum states of matter.