When the continuous symmetry of a physical system is spontaneously broken, two types of
collective modes typically emerge: the amplitude and the phase modes of the order …

The advent of intense ultrashort optical pulses spanning a frequency range from terahertz to
the visible has opened a new era in the experimental investigation and manipulation of …

Recently developed terahertz (THz) two-dimensional coherent spectroscopy (2DCS) is a
powerful technique to obtain materials information in a fashion qualitatively different from …

Illumination of light on matter normally causes heating and destroys the ordered ground
states. Despite this common understanding, recent advances in ultrafast light sources have …

Recent experiments with strong THz fields in both conventional and unconventional
superconductors have clearly evidenced a marked third-harmonic generation below the …

Recent findings of new Higgs modes in unconventional superconductors require a
classification and characterization of the modes allowed by nontrivial gap symmetry. Here …

Motivated by the recent experimental progress in studying conventional and unconventional
superconductors in a pump-probe setup, we perform a comprehensive theoretical analysis …

In multiband superconductors, multiple collective modes exist associated with the multiple
order parameters. Oscillations of the amplitude and the relative phase of the order …

We present a detailed theoretical investigation of the linear and nonlinear optical response
in a model system for a disordered d-wave superconductor. By evaluating the quasiparticle …

Cuprate high-T c superconductors are known for their intertwined interactions and the
coexistence of competing orders. Uncovering experimental signatures of these interactions …