论文标题
约瑟夫森等离子波的参数共振：yba $ _2 $ _2 $ cu $ _3 $ o $ o $ _ {6+x} $的光学放大层间超导的理论
Parametric resonance of Josephson plasma waves: A theory for optically amplified interlayer superconductivity in YBa$_2$Cu$_3$O$_{6+x}$
论文作者
论文摘要
集体模式之间的非线性相互作用在强相关电子系统的均衡动力学中起着明确的作用。理解和利用这些相互作用对于量子多体状态的照片控制至关重要。强度模式耦合的最令人惊讶的例子之一是双层YBA YBA $ _2 $ _2 $ _3 $ _3 $ o $ o $ _ {6+x} $ superconductors中的顶氧声子和约瑟夫森等离子体之间的相互作用。 Hu等人（2014）的实验。和Kaiser等。 （2014年）表明，在TC下，声子的照相兴趣会导致约瑟夫森等离子体边缘的增强和频移，而abovetc，即使在平衡反射率中没有明显的特征，abovETC也会引起等离子体的边缘。 Van Hoegen等人的最新实验。 （2019年）还观察到来自TC以下和伪随阶段的光启用的声子的约瑟夫森等离子体的参数产生。在本文中，我们介绍了由氧运动与平面超氟刚度之间的耦合引起的声子 - 平面三波相互作用的理论模型。基于该模型的等离物的参数不稳定性的分析给出了与实验观察结果一致的最不稳定的等离子的频率。 We also discuss how strong parametric excitation of Josephson plasmons can explain pump induced changes in the TeraHertz reflectivity of YBa$_2$Cu$_3$O$_{6+x}$ in the superconducting state, including frequency shifts and sharpening of Josephson plasmon edges, as well as appearance of a new peak around 2THz.该模型的一个有趣特征是，过度阻尼的约瑟夫森等离子体在平衡中没有任何可辨认的特征，而是在参数激发时会产生等离子体的边缘。我们建议这种机制在yba $ _2 $ _2 $ cu $ _3 $ o $ _ {6+x} $中解释了照片诱导的等离子体边缘。
Non-linear interactions between collective modes play a definitive role in far out of equilibrium dynamics of strongly correlated electron systems. Understanding and utilizing these interactions is crucial to photo-control of quantum many-body states. One of the most surprising examples of strong mode coupling is the interaction between apical oxygen phonons and Josephson plasmons in bilayer YBa$_2$Cu$_3$O$_{6+x}$ superconductors. Experiments by Hu et al (2014). and Kaiser et al. (2014) showed that below Tc, photo-excitation of phonons leads to enhancement and frequency shifts of Josephson plasmon edges, while aboveTc, photo-excited phonons induce plasmon edges even when there are no discernible features in the equilibrium reflectivity spectrum. Recent experiments by Van Hoegen et al. (2019) also observed parametric generation of Josephson plasmons from photo-excited phonons both below Tc and in the pseudogap phase. In this paper we present a theoretical model of phonon-plasmon three wave interaction arising from coupling between the oxygen motion and the in-plane superfluid stiffness. Analysis of the parametric instability of plasmons based on this model gives frequencies of the most unstable plasmons that are in agreement with experimental observations. We also discuss how strong parametric excitation of Josephson plasmons can explain pump induced changes in the TeraHertz reflectivity of YBa$_2$Cu$_3$O$_{6+x}$ in the superconducting state, including frequency shifts and sharpening of Josephson plasmon edges, as well as appearance of a new peak around 2THz. An interesting feature of this model is that overdamped Josephson plasmons do not give any discernible features in reflectivity in equilibrium, but can develop plasmon edges when parametrically excited. We suggest that this mechanism explains photo-induced plasmon edges in the pseudogap phase of YBa$_2$Cu$_3$O$_{6+x}$.
