论文标题
BEC-BCS跨界的非平衡动力学
Non-equilibrium dynamics across the BEC-BCS crossover
论文作者
论文摘要
我们研究了从BCS到BEC政权的时间依赖性Gutzwiller近似中强耦合超导体的淬灭动力学，并评估了与泵探测实验相关的不平衡瞬时瞬态光谱密度和光学电导率。顺序参数动力学的傅立叶变换揭示了频率$ω_j$，如BCS情况，该频谱差距控制。但是，我们发现了从BCS动力学到新的强耦合方案的交叉，其中特征频率$ω_U$与双占用波动相关联，控制顺序参数动力学。机制的变化接近动态相变。 $ω_j$和$ω_U$都产生了自动驱动的慢速行为振荡的复杂结构，这些结构在非平衡光学电导率中可见，由于超导幅度振幅振荡调节了双重占用率，因此出现侧带。类似的结果适用于CDW和SDW系统。
We investigate the quench dynamics of strongly coupled superconductors within the time-dependent Gutzwiller approximation from the BCS to the BEC regime and evaluate the out-of-equilibrium transient spectral density and optical conductivity relevant for pump probe experiments. Fourier transformation of the order parameter dynamics reveals a frequency $Ω_J$ which, as in the BCS case, is controlled by the spectral gap. However, we find a crossover from the BCS dynamics to a new strong coupling regime where a characteristic frequency $Ω_U$, associated to double occupancy fluctuations controls the order parameter dynamics. The change of regime occurs close to a dynamical phase transition. Both, $Ω_J$ and $Ω_U$ give rise to a complex structure of self-driven slow Rabi oscillations which are visible in the non-equilibrium optical conductivity where also side bands appear due to the modulation of the double occupancy by superconducting amplitude oscillations. Analogous results apply to CDW and SDW systems.
