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arXiv 0811.3736cond-mat.mes-hall
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量子级联结构中光学动力学和输运的密度矩阵理论:相干性的作用

Density-matrix theory of the optical dynamics and transport in quantum cascade structures: The role of coherence

C. Weber, A. Wacker, A. Knorr

摘要:

研究了量子级联激光器结构中相干性对非线性光学响应和稳态输运的影响。在微观密度矩阵方法中研究了泵浦-探测信号、时空分辨电子密度演化、子带布居动力学(Rabi flopping)以及稳态电流特性等非平衡效应。专注于固定的电流和最近观察到的增益振荡,它被发现,包括相干导致可观察到的相干效应在相反的参数制度关于之间的关系的水平加宽和隧道耦合跨越主注入势垒。这表明相干性在稳态输运和非线性光学动力学中起着互补作用,因为它导致了相反区域中的可测量效应。因此,对这种非平衡结构的完全相干考虑对于描述组合的光学和输运性质是必要的

英文摘要:

The impact of coherence on the nonlinear optical response and stationary transport is studied in quantum cascade laser structures. Nonequilibrium effects such as pump-probe signals, the spatio-temporally resolved electron density evolution, and the subband population dynamics (Rabi flopping) as well as the stationary current characteristics are investigated within a microscopic density-matrix approach. Focusing on the stationary current and the recently observed gain oscillations, it is found that the inclusion of coherence leads to observable coherent effects in opposite parameter regimes regarding the relation between the level broadening and the tunnel coupling across the main injection barrier. This shows that coherence plays a complementary role in stationary transport and nonlinear optical dynamics in the sense that it leads to measurable effects in opposite regimes. For this reason, a fully coherent consideration of such nonequilibrium structures is necessary to describe the combined optical and transport properties

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