Light-Driven Electron-Hole Bardeen-Cooper-Schrieffer-Like State in Bulk GaAs
Light-Driven Electron-Hole Bardeen-Cooper-Schrieffer-Like State in Bulk GaAs
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DOI：
10.1103/physrevlett.123.197401
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发表时间：
2019-11-08
影响因子：
8.6
通讯作者：
Shimano, Ryo
中科院分区：
文献类型：
--
作者：
Murotani, Yuta;Kim, Changsu;Shimano, Ryo
利用光泵浦-探测光谱研究了GaAs体材料中激子的光子修饰态。我们发现，在高密度区的激子图片不再有效的吸收边的高能量分支的修饰态不断演变成一个奇异的增强。将实验结果与基于半导体Bloch方程的模拟结果进行比较，我们发现，在这样一个高密度区域中的修饰态更好地被视为Bardeen-Cooper-Schriller类态，这在理论上预计将存在几十年。在看到修饰态可以看作是受外光场驱动的宏观相干态之后，我们还讨论了由于瞬态吸收中的库仑增强，光激发后修饰态到非相干态的退相干。
We investigate the photon-dressed state of excitons in bulk GaAs by optical pump-probe spectroscopy. We reveal that the high-energy branch of the dressed states continuously evolves into a singular enhancement at the absorption edge in the high-density region where the exciton picture is no longer valid. Comparing the experimental result with a simulation based on semiconductor Bloch equations, we show that the dressed state in such a high-density region is better viewed as a Bardeen-Cooper-Schrieffer-like state, which has been theoretically anticipated to exist over decades. Having seen that the dressed state can be regarded as a macroscopic coherent state driven by an external light field, we also discuss the decoherence from the dressed state to an incoherent state after the photoexcitation in view of the Coulomb enhancement in the transient absorption.