Advith's Calendar

Abstract: Quantum materials exhibit emergent phenomena including superconductivity, charge order, magnetism, and topological phases, with promising applications in next-generation technologies. A central goal of condensed matter physics is to understand and control the fundamental interactions that give rise to these complex collective states. The relevant elementary excitations and collective modes in such systems often lie the low-energy terahertz (THz) regime, a spectral range that has historically been challenging to access experimentally. 

In this talk, I will present two complementary spectroscopic techniques that provide new insight into low-energy charge dynamics in correlated quantum materials. First, I will introduce momentum-resolved electron energy-loss spectroscopy (M-EELS), which enables direct measurements of the dynamics at THz frequencies and beyond as a function of both energy and momentum. Applying this method to a prototypical charge-density-wave material reveals unconventional charge dynamics and demonstrates the first direct experimental observation of a divergent susceptibility in these systems, a phenomenon theoretically predicted in 1979 [1]. I will then introduce THz two-dimensional coherent spectroscopy (THz 2DCS), a nonlinear approach for probing interaction-driven electronic responses and highlight some applications of this method [2, 3]. Together, these techniques establish a multimodal framework for uncovering how collective electronic orders emerge in quantum materials and suggest new strategies for controlling emergent phases.

Publication reference:

1.   Chaudhuri et al., Proc. Natl. Acad. Sci. U.S.A. 122 (25) e2424430122 (2025).

2.   Mahmood, Chaudhuri et al., Nature Physics 17, 627-631 (2021).

3.   Chaudhuri et al., arxiv:2503.15646 (2025).