Amplitude Mode in a Multigap Superconductor MgB2 Investigated by Terahertz Two-Dimensional Coherent SpectroscopyRemoveKota Katsumi, Jiahao Liang, Ralph Romero, III, Ke Chen, Xiaoxing Xi, and N. P. ArmitagePhys. Rev. Lett. 135, 036902 (2025)
