The ultrafast manipulation of quantum material has led to many novel and significant discoveries. Among them, the light-induced transient superconductivity in cuprates achieved by melting competing stripe orders represents a highly appealing accomplishment. However, recent investigations have shown that the notion of photoinduced superconductivity remains a topic of controversy, and its elucidation solely through $c$-axis time-resolved terahertz spectroscopy remains an arduous task. Here, we measure the in-plane and out-of-plane transient terahertz responses simultaneously in the stripe-ordered nonsuperconducting ${\mathrm{La}}_{2-x}{\mathrm{Ba}}_x{\mathrm{CuO}}_4$ after near-infrared excitations. We find that although a pump-induced reflectivity edge appears in the $c$-axis reflectance spectrum, the reflectivity along the ${\mathrm{CuO}}_2$ planes decreases simultaneously, indicating an enhancement in the scattering rate of quasiparticles. This in-plane transient response is clearly distinct from the features associated with superconducting condensation. Therefore, we conclude the out-of-plane transient responses cannot be explained by an equivalent of Josephson tunneling. Notably, those pump-induced terahertz responses remain consistent even when we vary the near-infrared optical pump wavelengths and hole concentrations. Our results provide critical evidence that transient three-dimensional superconductivity cannot be induced by melting the competing stripe orders with pump pulses whose photon energy is much higher than the superconducting gap of cuprates.

中文翻译：

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在 La2−xBaxCuO4 中不引入超导性的竞争条带序的光诱导熔化

量子材料的超快操控带来了许多新颖且重大的发现。其中，通过熔化竞争条纹顺序实现的铜酸盐光致瞬态超导性代表了一项非常吸引人的成就。然而，最近的研究表明，光致超导的概念仍然是一个有争议的话题，它的阐明只能通过$C$轴时间分辨太赫兹光谱仍然是一项艰巨的任务。在这里，我们同时测量了带状有序非超导材料中的面内和面外瞬态太赫兹响应${拉}_{2-X}{巴}_X{\mathrm{氧化铜}}_4$近红外激发后。我们发现，尽管泵浦引起的反射率边缘出现在$C$轴反射光谱，沿轴的反射率${\mathrm{氧化铜}}_2$平面同时减小，表明准粒子的散射率增强。这种面内瞬态响应明显不同于与超导凝结相关的特征。因此，我们得出的结论是，面外瞬态响应不能用约瑟夫森隧道效应的等价解释。值得注意的是，即使我们改变近红外光泵浦波长和空穴浓度，这些泵浦引起的太赫兹响应仍然保持一致。我们的结果提供了关键的证据，证明瞬态三维超导性不能通过用泵浦脉冲熔化竞争的条带顺序来诱导，而泵浦脉冲的光子能量远高于铜酸盐的超导带隙。