Enhancement of superexchange pairing in the periodically driven Hubbard model
Enhancement of superexchange pairing in the periodically driven Hubbard model
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DOI：
10.1103/physrevb.96.085104
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发表时间：
2017-08-01
影响因子：
3.7
通讯作者：
Jaksch, D.
中科院分区：
文献类型：
--
作者：
Coulthard, J. R.;Clark, S. R.;Jaksch, D.
最近对铜酸盐和碱掺杂富勒烯化物进行的实验表明，可以通过光调制在平衡临界温度之上诱导超导的关键特征。这些在不同物理系统中的观察结果可能表明了普遍的潜在机制。人们已经提出了多种理论，但这些理论要么考虑特定的特征，例如竞争不稳定性，要么关注传统的 BCS 型超导性。在这里，我们证明周期性驱动可以增强强相关系统中的电子配对。着眼于掺杂哈伯德模型的强排斥极限，我们研究了带隙内、空间不均匀的现场调制。我们证明，这种调制大大减少了电子跳跃，同时通过驱动诱导的虚拟电荷激发维持超交换相互作用和对跳跃。我们从零温度和有限温度初始状态开始计算一维情况的实时动力学，并且我们表明，在非平衡多体状态下，增强的单重态对相关性会快速而稳健地出现。我们的结果揭示了一种基本配对机制，该机制可能支撑一些强相关量子材料中的光感超导性。
Recent experiments performed on cuprates and alkali-doped fullerides have demonstrated that key signatures of superconductivity can be induced above the equilibrium critical temperature by optical modulation. These observations in disparate physical systems may indicate a general underlying mechanism. Multiple theories have been proposed, but these either consider specific features, such as competing instabilities, or focus on conventional BCS-type superconductivity. Here we show that periodic driving can enhance electron pairing in strongly correlated systems. Focusing on the strongly repulsive limit of the doped Hubbard model, we investigate in-gap, spatially inhomogeneous, on-site modulations. We demonstrate that such modulations substantially reduce electronic hopping, while simultaneously sustaining superexchange interactions and pair hopping via driving-induced virtual charge excitations. We calculate real-time dynamics for the one-dimensional case, starting from zero-and finite-temperature initial states, and we show that enhanced singlet-pair correlations emerge quickly and robustly in the out-of-equilibrium many-body state. Our results reveal a fundamental pairing mechanism that might underpin optically induced superconductivity in some strongly correlated quantum materials.