Terahertz probes of quantum matter: from pairing symmetry to high harmonics
Quantum materials often harbor emergent orders and phases that reveal themselves at low-energy scales, around 1 to 10 meV. To investigate these collective behaviors, we turn to the terahertz energy regime—a crucial window for probing and controlling quantum phenomena. In this talk, I will present our latest breakthroughs in unraveling the superconducting gap structure of the newly discovered unconventional nickelate superconductors— a topic that has sparked intense debate and remains unresolved. Using both linear and nonlinear terahertz spectroscopy, we uncovered multiple evidence to demonstrate a cuprate-like d-wave gap structure in nickelate superconductors, providing key insights to steer future research in this field. Expanding beyond understanding, I will broaden the discussion to the manipulation of quantum materials through light. I will show how we harness intense terahertz pulses to drive the electronic structure of a Dirac semimetal, leading to the observation of record-breaking terahertz high harmonics. Our findings position topological materials as promising platforms for delving into high harmonic generation and strong-field physics.
Brief Bio: Bing Cheng earned his Ph.D. in Johns Hopkins University in Sep 2019. Then he moved to Stanford, and Ames National Lab, working as a postdoc researcher. At present, He is working as a research fellow in Prof. Mengkun Liu’s group at Stony Brook University. His research mainly focuses on discovering and understanding exotic quantum phases of matter using a suite of terahertz optics