In our lab, we apply advanced nanodevice fabrications and laser spectroscopy measurements, especially THz methodology and nonlinear optics, to gain insights into meV-eV excitations and their quantum light-matter interaction in unconventional materials, often at an ultrafast time scale. We are particularly interested in the following research directions.
Antiferromagnetism in low dimensions
Two-dimensional antiferromagnetism (2D AFM) plays an essential role in various correlated phenomena e.g., unconventional superconductivity and quantum spin liquids. With advanced optical techniques, we are trying to understand and further control magnetic ground states and the elementary excitations of low-dimensional AFM, as well as the interplay between other degrees of freedom.
Boosting the operation frequency of spintronic devices beyond gigahertz (GHz) toward THz regime is a long-sought goal of spintronic research. More importantly, by entering the THz regime, it opens up intriguing opportunities offered by AFM materials. Many AFM magnons locate within the THz range, those are previously hard to access by conventional electronic detection, due to their ultrahigh frequencies and the insulating nature of many AFM materials.
Non-equilibrium dynamics of quantum phases
In condensed matter physics, non-equilibrium dynamics of quantum phases is one of the most intriguing fields and remains largely unexplored. Our approach is to coherently drive the quantum phases with intense THz/IR pulses, which directly interact with the elementary excitations of the system, and minimize the excess photon energy and thermal decoherence. We not only focus on the ultrafast dynamics of quantum matter, but also explore the strong light-matter interaction and possible light-induced new phases.
Our spectroscopy techniques
We design and construct various optical spectroscopy systems to address the scientific questions we interested in. Our spectroscopy capabilities are ranging from continuous-wave spectroscopy, e.g., photoluminescence, MORE, and Raman scattering, to spectroscopy systems based on ultrafast oscillators and amplifiers, such as THz time-domain spectroscopy, transient absorption, second-harmonic generation. We also closely collaborate with ultrafast electron diffraction (UED) group and time-resolved Xray group to gain insights on the ultrafast lattice dynamics in quantum materials.