We numerically prove photoinduced $η$-pairing in a half-filled fermionic Hubbard chain at both zero and finite temperature. The result, obtained by combining the matrix-product-state based infinite time-evolving block decimation technique and the purification method, applies to the thermodynamic limit. Exciting the Mott insulator by a laser electric field docked on via the Peierls phase, we track the time-evolution of the correlated many-body system and determine the optimal parameter set for which the nonlocal part of the $η$-pair correlation function becomes dominant during the laser pump at zero and low temperatures. These correlations vanish at higher temperatures and long times after pulse irradiation. In the high laser frequency strong Coulomb coupling regime we observe a remnant enhancement of the Brillouin-zone boundary pair-correlation function also at high temperatures, if the Hubbard interaction is about a multiple of the laser frequency, which can be attributed to an enhanced double occupancy in the virtual Floquet state.
Universität Greifswald（格赖夫斯瓦尔德大学）；Deutsches Zentrum für Luft- und Raumfahrt (DLR)（德国航空航天中心）；Friedrich-Alexander-Universität Erlangen-Nürnberg（埃尔朗根-纽伦堡大学）
Utilizing the time-dependent density-matrix renormalization group technique, we numerically prove photoinduced pairing states in the extended Falicov-Kimball model (EFKM) at half filling, both with and without internal SU(2) symmetry. In the time-dependent photoemission spectra an extra band appears above the Fermi energy after pulse irradiation, indicating an insulator-to-metal transition. Even in the absence of the SU(2) structure, the pair correlations are enhanced during the pump, and afterwards decrease over time. This implies the possible metallization of Ta$_2$NiSe$_5$, a strong candida…
Real-time dynamics techniques have proven increasingly useful in understanding strongly correlated systems both theoretically and experimentally. By employing unbiased time-resolved exact diagonalization, we study pump dynamics in the two-dimensional plaquette Hubbard model, where distinct hopping integrals $t_h$ and $t_h^\prime$ are present within and between plaquettes. In the intermediate coupling regime, a significant enhancement of $d$-wave superconductivity is observed and compared with that obtained by simple examination of expectation values with the eigenstates of the Hamiltonian. Our…
Giant Resonant Enhancement of Photoinduced Dynamical Cooper Pairing, far above $T_c$
Harvard University（哈佛大学）；ETH Zürich（苏黎世联邦理工学院）；Max Planck Institute for the Physics of Complex Systems（马克斯·普朗克复杂系统物理研究所）；Max Planck Institute for the Structure and Dynamics of Matter（马克斯·普朗克物质结构动力学研究所）；University of Oxford（牛津大学）
Photoinduced two-step insulator-metal transition in Ti4O7 by ultrafast time-resolved optical reflectivity
我们报告的超快时间分辨光学反射率在Ti4 O 7的热载流子动力学的系统调查。我们发现了它的两步绝缘体-金属（I-M）相变的瞬态指示，即在Tc 1处发生从长程序双极化子低温绝缘（LI）相到无序双极化子高温绝缘（HI）相和在Tc 2处到自由载流子金属（M）相的两个相变。结果表明，随着泵浦能量密度的增加，光激发可以有效地降低Tc 1和Tc 2，从而实现I-M跃迁的光控制。我们解决的相图，提供了一个框架的光诱导的I-M转变，并有助于潜在的使用Ti4 O 7的光电和热电器件。
近藤效应起源于自旋-自旋相互作用对局域磁矩的屏蔽，广泛存在于非人工磁性材料、人工量子点和碳纳米管中。在以量子信息应用为目标的基于量子点或碳纳米管的器件中，可以通过栅极电压、磁场或光来调谐近藤效应。然而，在非人工材料中对近藤效应的操纵还没有被彻底研究;特别是，人工创造的近藤效应仍然没有被探索。然而，根据该主题研究，提出了在非人工材料$p$型半导体CeZn $_{3}$ P $_{3}$中光学产生近藤效应的新途径。在连续波激光二极管对材料进行可见光照射下，出现了近藤效应，并最终通过光致电阻率揭示了该效应，该电阻率清楚地表现出对数温度依赖性。相比之下，基于La的化合物（LaZn $_{3}$ P $_{3}$）在类似照明下仅显示正常的金属行为。与人工系统中的近藤效应相比，光致近藤效应在更高的温度下发生，不仅为量子信息/计算器件而且为磁光器件的操作提供了潜在的新的操作范围，从而扩展了基于近藤效应的器件应用范围。
Photoinduced Suppression of Superconductivity in Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+δ}$
高温超导体中的超导性是通过将电荷载流子引入到含有CuO $_2$平面的铜氧化物绝缘体中来实现的。这些CuO $_2$平面的扰动通过强烈影响电子环境来抑制超导性。本文利用Cu离子在CuO $_2$平面上的光致电子改性研究了Bi $_2$ Sr $_2$ Ca $_2$ Cu $_3$ O $_{10+δ}$中局域微扰的影响。这种方法已用于抑制超导转变温度T $_c$。我们表明，我们的结果光致抑制的超导性是一致的情况下，基于钉扎的波动条纹在Bi $_2$ Sr $_2$ Ca $_2$ Cu $_3$ O $_{10+δ}$。
Recently, kagome lattice metal AV$_3$Sb$_5$ (A = K, Rb, Cs) family has received wide attention due to its presence of superconductivity, charge density wave (CDW) and peculiar properties from topological nontrivial electronic structure. With time-resolved pump-probe spectroscopy, we show that the excited quasiparticle relaxation dynamics can be explained by formation of energy gap below the phase transition being similar to a usual second-order CDW condensate, by contrast, the structure change is predominantly first order phase transition. Furthermore, no CDW amplitude mode is identified in th…
Pairing interactions and pairing mechanism in high temperature copper oxide superconductors
在未掺杂的母体铜氧化物的极化子结合能E_{p}已被确定为约1.0 eV的反铁磁有序温度的非常规氧同位素效应。推导出的E_{p}值与由独立光学数据估计的值和由测量的介电常数理论估计的值在定量上是一致的。在最佳掺杂的铜酸盐中观察到的面内超载流子质量上的大量氧同位素效应表明极化子被束缚到库珀对中。我们还确定了声子模式，强烈耦合到传导电子的角度分辨的光电子能谱，隧穿光谱，和光学数据。我们一贯表明，有一个非常强的电子-声子耦合功能，在声子能量约20毫电子伏沿波腹方向，这种耦合变得越来越弱的对角方向。我们进一步指出，铜酸盐的高温超导电性是由强的电子-声子耦合、极化子效应以及与2 eV Cu-O电荷转移涨落的显著耦合引起的。
Strongly interacting fermionic atoms are shown to develop $η$-pairing superfluid correlations in a nonequilibrium steady state in the presence of spontaneous emission of light from atoms. On the basis of the Hubbard model subject to spontaneous decay between internal spin states, we show that prohibition of radiative decay due to the Pauli exclusion principle and destructive interference between doublon-decay processes lead to nonequilibrium $η$ pairing. Because of the non-thermal nature of the steady state, pair correlations arise even from a completely uncorrelated infinite-temperature initi…
The orbital multiplicity in multiband superconductors yields orbital differentiation in normal-state properties, and can lead to orbital-selective spin-fluctuation Cooper pairing. This phenomenon has become increasingly pivotal in clarifying the pairing 'enigma' particularly for multiband high-temperature superconductors. In one-unit-cell (1-UC) FeSe/SrTiO3, the thinnest and highest-Tc member of iron-based superconductors, the standard electron-hole Fermi pocket nesting scenario is apparently not applicable since the Gamma-centered hole pockets are absent, so the actual pairing mechanism is th…
