Welcome to the Liu Group
Ultrafast Optics
Capturing electronic motion one photon at a time
Our research focuses on understanding:
The structure-function relationship in quantum materials and chemical systems. Material functions or chemical activities, which are essentially how these systems respond to external stimuli, often involve the excitation of coupled various degrees of freedom such as charge, lattice and spins. Ultrafast X-ray spectroscopy can separate the role of electronic, structural, spin and elemental responses, providing a detailed understanding of how ultrafast dynamics at the unit-cell level ultimately determines materials properties and functions.
Light-synthesized non-equilibrium states. In light-matter interactions, when the laser field strength is comparable to the intrinsic bond strength of the material, the phonon field will hybridize with matter, creating a highly non-equilibrium laser-driven transient state. In this regime, many new phenomena occur, including high-harmonic generation, strong-field driven charge transfer, petahertz electronics, and light-renormalized many-body interaction. We are interested in using nonlinear spectroscopy and X-ray techniques to understand the creation and evolution of these light-synthesized non-equilibrium states. More importantly, we want to explore how intense light can be used to control material properties, including exploring new transient phases of quantum materials and modulating catalytic behaviors.