Title: Dissecting coupled orders in a terahertz-driven electron-doped cuprate Show Chinese title

Title: 在太赫兹驱动的电子掺杂铜氧化物中分解耦合序

Abstract: The interplay between superconductivity and charge density wave has often been studied from an equilibrium point of view. For example, using static tuning knobs such as doping, magnetic field and pressure, superconductivity can be enhanced or suppressed. The resulting effect on the co-existing charge density wave order, if any, is judged by variations in its ground state properties such as the ordering temperature or the spatial correlation. Such an approach can be understood as coordinated static displacements of two coupled order parameters within a Ginzburg-Landau description, evincing their interplay as either co-operative or competing but does not provide further microscopic information about the interaction. In order to assess such information, we dynamically perturb both orders from equilibrium and observe their coupling directly in the time-domain. We show that high-field multicycle terahertz pulses drive both the Higgs amplitude fluctuations of the superconducting order as well as collective fluctuations of the charge order in an electron-doped cuprate, resulting in characteristic third harmonic generation. A notable time delay is manifested between their respective driven dynamics. We propose that this may signify the important energy scale describing their coupling or imply a terahertz field-depinned charge density wave that destroys macroscopic superconductivity. Our work demonstrates a holistic approach for investigating coupled superconducting and charge density wave orders, which may shed novel light on their intertwined presence and widespread fluctuations in many classes of unconventional superconductors. Show Chinese abstract

Abstract: 超导与电荷密度波之间的相互作用通常从平衡的角度进行研究。 例如，通过使用静态调节旋钮（如掺杂、磁场和压力）可以增强或抑制超导性。 如果存在共存的电荷密度波序，则可以通过其基态性质（如有序温度或空间关联性）的变化来判断其产生的影响。 这种方法可以理解为在Ginzburg-Landau描述下两个耦合序参量的协调静态位移，揭示它们的相互作用为合作或竞争，但并未提供关于相互作用的更多微观信息。 为了评估此类信息，我们动态扰动这两个序参量使其偏离平衡，并在时域中直接观察它们的耦合。 我们展示了高强度多周期太赫兹脉冲驱动了电子掺杂铜氧化物中的超导序的Higgs振幅涨落以及电荷序的集体涨落，从而导致了特征性的三倍频产生。 它们各自的驱动动力学之间表现出显著的时间延迟。 我们提出这可能标志着描述它们耦合的重要能量尺度，或者意味着一种破坏宏观超导性的太赫兹场失稳电荷密度波。 我们的工作展示了一种全面的方法来研究耦合的超导和电荷密度波序，这可能会为许多类非常规超导体中它们交织存在和广泛波动提供新的见解。