Theory of parametrically amplified electron-phonon superconductivity
Theory of parametrically amplified electron-phonon superconductivity
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DOI：
10.1103/physrevb.96.014512
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发表时间：
2017-07-19
影响因子：
3.7
通讯作者：
Demler, Eugene
中科院分区：
文献类型：
--
作者：
Babadi, Mehrtash;Knap, Michael;Demler, Eugene
强关联材料中有序相的超快光学操纵是一个具有重要理论、实验和技术意义的课题。受最近富勒烯光致超导实验的启发[M. Mitrano等人，Nature（伦敦）530，461（2016）]，我们开发了具有晶格非线性的驱动电子-声子系统中的光致超导性的综合理论。在类比与参量放大器的操作，我们展示了如何外部驱动和晶格非线性之间的相互作用，导致显着增强有效的电子-声子耦合。我们提供了一个详细的和公正的研究的非平衡动力学的驱动系统使用实时的绿色函数技术。为此，我们开发了一个Floquet推广的Migdal-Eliashberg理论，并推导出一组数值上易于处理的量子Floquet-Boltzmann动力学方程的耦合电子-声子系统。我们研究了参量声子产生和电子加热在破坏瞬态超导态中的作用。最后，我们预测的瞬态形成的电子Floquet带的时间和角度分辨的光电子能谱实验的结果所提出的机制。
Ultrafast optical manipulation of ordered phases in strongly correlated materials is a topic of significant theoretical, experimental, and technological interest. Inspired by a recent experiment on light-induced superconductivity in fullerenes [M. Mitrano et al., Nature (London) 530, 461 (2016)], we develop a comprehensive theory of light-induced superconductivity in driven electron-phonon systemswith lattice nonlinearities. In analogy with the operation of parametric amplifiers, we show how the interplay between the external drive and lattice nonlinearities lead to significantly enhanced effective electron-phonon couplings. We provide a detailed and unbiased study of the nonequilibrium dynamics of the driven system using the real-time Green's function technique. To this end, we develop a Floquet generalization of the Migdal-Eliashberg theory and derive a numerically tractable set of quantum Floquet-Boltzmann kinetic equations for the coupled electron-phonon system. We study the role of parametric phonon generation and electronic heating in destroying the transient superconducting state. Finally, we predict the transient formation of electronic Floquet bands in time-and angle-resolved photoemission spectroscopy experiments as a consequence of the proposed mechanism.