biostudies-literatureKim MJEuropean Research Councileadi7598https://www.ebi.ac.uk/biostudies/studies/S-EPMC10942118biostudies-literatureUnknown10(11)Ultrafast optical control of quantum systems is an emerging field of physics. In particular, the possibility of light-driven superconductivity has attracted much of attention. To identify nonequilibrium superconductivity, it is necessary to measure fingerprints of superconductivity on ultrafast timescales. Recently, nonlinear THz third-harmonic generation (THG) was shown to directly probe the collective degrees of freedoms of the superconducting condensate, including the Higgs mode. Here, we extend this idea to light-driven nonequilibrium states in superconducting La_2-<i>x</i>Sr<i>_x</i>CuO₄, establishing an optical pump-THz-THG drive protocol to access the transient superconducting order-parameter quench and recovering on few-picosecond timescales. We show Science advancesTracing the dynamics of superconducting order via transient terahertz third-harmonic generation.PMC10942118951215101044657Ilyakov IKim GLogvenov GKeimer BManske DKaiser SCristiani GDeinert JCPonomaryov AUdina MHaenel RPuviani Mde Oliveira TVAGKovalev SKim MJBenfatto LfalseTracing the dynamics of superconducting order via transient terahertz third-harmonic generation.Ultrafast optical control of quantum systems is an emerging field of physics. In particular, the possibility of light-driven superconductivity has attracted much of attention. To identify nonequilibrium superconductivity, it is necessary to measure fingerprints of superconductivity on ultrafast timescales. Recently, nonlinear THz third-harmonic generation (THG) was shown to directly probe the collective degrees of freedoms of the superconducting condensate, including the Higgs mode. Here, we extend this idea to light-driven nonequilibrium states in superconducting La_2-<i>x</i>Sr<i>_x</i>CuO₄, establishing an optical pump-THz-THG drive protocol to access the transient superconducting order-parameter quench and recovering on few-picosecond timescales. We show 2024-01-01T00:00:00Z2024 Mar2025-04-04T20:17:47.912Z2025-04-04T20:17:47.912ZS-EPMC109421183848936310.1126/sciadv.adi7598