Sum-over-states versus quasiparticle pictures of coherent correlation spectroscopy of excitons in semiconductors: Femtosecond analogs of multidimensional NMR
Sum-over-states versus quasiparticle pictures of coherent correlation spectroscopy of excitons in semiconductors: Femtosecond analogs of multidimensional NMR
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半导体中激子相干相关光谱的状态求和与准粒子图：多维核磁共振的飞秒模拟
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发表时间：
2007
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通讯作者：
D. Abramavičius
中科院分区：
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作者：
S. Mukamel;R. Oszwałdowski;D. Abramavičius
基于激子对超快脉冲序列的非线性光学响应的二维相关光谱2DCS可能为研究半导体中的载流子动力学提供一些独特的见解。2DC最显著的特征，即交叉峰，可以通过包含多体本征态的状态总和图来最好地理解。然而，半导体的光学响应通常是通过求解动力学变量的截断运动方程来计算的，这导致了一幅准粒子图像。在这项工作中，我们推导了在不同的相位匹配方向上产生的四波混频信号的格林函数表达式，并用它们来建立两幅图像之间的联系。指出了Frenkel激子、硬核玻色子和振动激子、软核玻色子之间的形式联系。
Two-dimensional correlation spectroscopy 2DCS, based on the nonlinear optical response of excitons to sequences of ultrafast pulses may provide some unique insights into carrier dynamics in semiconductors. The most prominent feature of 2DCS, cross peaks, can best be understood using a sum-over-states picture involving the many-body eigenstates. However, the optical response of semiconductors is usually calculated by solving truncated equations of motion for dynamical variables, which result in a quasiparticle picture. In this work we derive Green’s function expressions for the four wave mixing signals generated in various phase-matching directions and use them to establish the connection between the two pictures. The formal connection with Frenkel excitons hard-core bosons and vibrational excitons soft-core bosons is pointed out.