Higgs oscillations in time-resolved optical conductivity
Higgs oscillations in time-resolved optical conductivity
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DOI：
10.1103/physrevb.100.174515
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发表时间：
2019-11-21
影响因子：
3.7
通讯作者：
Kemper, A. F.
中科院分区：
文献类型：
--
作者：
Kumar, A.;Kemper, A. F.
超导体失去平衡是研究其平衡性质和控制超导态的一条很有前途的途径。非平衡超导体经常被用时间分辨光学电导测量来研究。因此，在抽运驱动的非平衡态中的超导状态的表征需要在时间域中仔细地注意。我们用非平衡Keldysh方法计算了抽运超导态的时间分辨光学电导。通过泛函推导，得到了经过全顶点修正后的光学电导率，并用它来表征暂态超导态。暂态光学电导在时间域上表现出超导序参数的抑制。随后序参数的恢复表现出与希格斯振幅模式相对应的振荡行为，并且可以在光谱的几个部分看到。
Driving superconductors out of equilibrium is a promising avenue to study their equilibrium properties as well as to control the superconducting state. Nonequilibrium superconductors are often studied using time-resolved optical conductivity measurements. Thus, the characterization of a superconducting state in a pump driven nonequilibrium state requires careful attention in the time domain. We calculate the time-resolved optical conductivity of a pumped superconducting state using a nonequilibrium Keldysh approach. Through functional derivation, the optical conductivity is obtained with full vertex corrections and used to characterize the transient superconducting state. The transient optical conductivity shows the suppression of the superconducting order parameter in the time domain. The subsequent recovery of the order parameter exhibits oscillatory behavior that corresponds to the Higgs amplitude mode, and may be seen in several parts of the spectrum.