Replication Data for: Chirped pulse control over the melting of superconductors

Strong field terahertz pulses are increasingly used to excite and control quantum materials at the ultrafast timescale. They have found widespread application by enabling direct addressing of the superconducting gap or Josephson resonances and are essential in Higgs spectroscopy. Large non-linear optical signals can be induced by the strong coupling of the THz and superconducting degrees of freedom. However, far less attention has been paid to the strong bidirectional coupling between field and material this implies. Here, we use the framework of the time-dependent Ginzburg-Landau equations to study the full field and material evolution of a superconductor driven by strong field terahertz pulses. We find that at high field strengths, the backreaction of the superconductor induces large changes to the driving pulse, which in turn leads to a runaway melting of the superconducting condensate. This results in a surprisingly large sensitivity to the initial driving pulse chirp, enabling these purely dynamical changes to produce order of magnitude differences in the level of melting. We also find large-scale spectral shifting of the driving pulse to occur in just a few hundred nanometers of propagation through a superconductor. We attribute these effects to an inverse plasma redshift, in which the driving field breaks Cooper pairs and decreases the free-electron mobility, analogous to reducing the density of a plasma.

强场太赫兹脉冲（strong field terahertz pulses）正日益被用于超快时间尺度下激发并调控量子材料。其可直接寻址超导能隙或约瑟夫森共振，因此获得了广泛应用，且在希格斯光谱学（Higgs spectroscopy）中不可或缺。太赫兹与超导自由度的强耦合可诱导出强烈的非线性光学信号。然而，此类强耦合所蕴含的场与材料间的双向耦合却鲜有研究。本文采用含时金兹堡-朗道方程（time-dependent Ginzburg-Landau equations）框架，研究强场太赫兹脉冲驱动下超导体的场与材料完整演化过程。我们发现，在高场强条件下，超导体的反向作用会对驱动脉冲产生显著改变，进而导致超导凝聚体（superconducting condensate）发生失控熔化。这一现象使得系统对初始驱动脉冲啁啾展现出惊人的高灵敏度，此类纯动力学变化可导致熔化程度产生数量级的差异。我们还发现，驱动脉冲在超导体中仅传播数百纳米即可发生大规模频谱偏移。我们将这些效应归因于逆等离子体红移（inverse plasma redshift）：驱动场破坏库珀对（Cooper pairs）并降低自由电子迁移率，这类似于等离子体密度的降低。