Higgs spectroscopy is a new and emergent field [1-3] that allows to classify and determine the superconducting order parameter by means of ultra-fast optical spectroscopy. There are two ways to activate the Higgs mode in superconductors, namely a single-cycle ‘quench’ or an adiabatic, multicycle ‘drive’ pulse, both illustrated in Figure 1. In the talk I will review and report on the latest progress on Higgs spectroscopy, in particular on the role of the third-harmonic-generation (THG) [4-6] and the possible IR-activation of the Higgs mode by impurities or external dc current [7,8]. I also provide new predictions for time-resolved ARPES experiments in which, after a quench, a continuum of Higgs mode is observable and a phase information of the superconducting gap function would be possible to extract [9]. As a recent milestone, I discuss recent results on Non-Equilibrium Anti-Stokes Raman Scattering (NEARS) [10] and on two-dimensional coherent spectroscopy [11] where the Higgs mode has been observed experimentally. Also, we have extended our approach to time-reversal superconductors [12] and find a variety of new possible Higgs modes. Finally, going beyond the BCS limit, we present an analytical calculation and find a true pole of the Higgs mode that increases its strength [13].

References

[1] L. Schwarz, D. Manske et al., Nat. Commun. 11, 287 (2020).

[2] L. Schwarz and D. Manske, Phys. Rev. B 101, 184519 (2020).

[3] H. Chu, S. Kaiser, D. Manske et al., Nat. Commun. 11, 1793 (2020).

[4] L. Schwarz. R. Haenel, and D. Manske, Phys. Rev. B 104, 174508 (2021).

[5] H. Chu, S. Kaiser, D. Manske et al., Nature Commun. 14, 1343 (2023).

[6] M.-J. Kim, S. Kaiser, D. Manske et al., Sci. Adv. 10, 3adi7598 (2024).

[7] M. Puviani, L. Schwarz, X.-X. Zhang, S. Kaiser, and D. Manske, Phys. Rev. B 101, 220507 (2020).

[8] R. Haenel, P. Froese, D. Manske, and L. Schwarz, Phys. Rev. B 104, 134504 (2021).

[9] L.Schwarz, B. Fauseweh, and D. Manske, Phys. Rev. B 101, 224510 (2020).

[10] T. Glier, D. Manske et al.,Nature Comm. 16, 702 (2025).

[11] M. Puviani, R. Haenel, and D. Manske, Phys. Rev. B 107, 094501 (2023).

[12] S. Neri, W. Metzner, and D. Manske, Phys. Rev. B 112, 224502 (2025).

[13] S. Tian, N. Tsuji, and D. Manske, arXiv:2604.15120 (2026).