论文标题
将广义的kadanoff-baym ansatz与整个kadanoff-baym方程式进行比较，以使激子绝缘子从平衡中进行比较
Comparing the generalized Kadanoff-Baym ansatz with the full Kadanoff-Baym equations for an excitonic insulator out of equilibrium
论文作者
论文摘要
我们调查了激发剂（EI）中的不平衡动力学，并通过有限动量与激光 - 渗水激发扰动，并突然耦合到费米子浴场。使用完整的非平衡绿色函数方法和第二次出生近似值内的广义Kadanoff-Baym Ansatz（GKBA）解决了激子阶参数的瞬态动力学。激光脉冲激发后两种方法之间的比较表明，在弱和中间的照片掺杂方案中良好的一致性。相比之下，GKBA解决的激光脉冲动力学在强烈的激发后不会显示出激发序的完全融化。取而代之的是，我们观察到激子阶参数的持续振荡，其主要频率由重新归一化的平衡带隙给出。这种异常行为可以通过耦合到外部浴场来克服GKBA形式主义，从而导致EI系统向正常状态过渡。我们分析了系统的长时间演变，并区分了与脱落和热化有关的衰减时间尺度。
We investigate out-of-equilibrium dynamics in an excitonic insulator (EI) with a finite momentum pairing perturbed by a laser-pulse excitation and a sudden coupling to fermionic baths. The transient dynamics of the excitonic order parameter is resolved using the full nonequilibrium Green's function approach and the generalized Kadanoff-Baym ansatz (GKBA) within the second-Born approximation. The comparison between the two approaches after a laser pulse excitation shows a good agreement in the weak and the intermediate photo-doping regime. In contrast, the laser-pulse dynamics resolved by the GKBA does not show a complete melting of the excitonic order after a strong excitation. Instead we observe persistent oscillations of the excitonic order parameter with a predominant frequency given by the renormalized equilibrium bandgap. This anomalous behavior can be overcome within the GKBA formalism by coupling to an external bath, which leads to a transition of the EI system towards the normal state. We analyze the long-time evolution of the system and distinguish decay timescales related to dephasing and thermalization.
