Physics Department, School of Natural Sciences, University of Patras, Patras 265 04, Greece.
J Phys Condens Matter. 2013 Jan 30;25(4):045304. doi: 10.1088/0953-8984/25/4/045304. Epub 2012 Dec 20.
We study optical effects in a hybrid system composed of a semiconductor quantum dot and a spherical metal nanoparticle that interacts with a weak probe electromagnetic field. We use modified nonlinear density matrix equations for the description of the optical properties of the system and obtain a closed-form expression for the linear susceptibilities of the quantum dot, the metal nanoparticle, and the total system. We then investigate the dependence of the susceptibility on the interparticle distance as well as on the material parameters of the hybrid system. We find that the susceptibility of the quantum dot exhibits optical transparency for specific frequencies. In addition, we show that there is a range of frequencies of the applied field for which the susceptibility of the semiconductor quantum dot leads to gain. This suggests that in such a hybrid system quantum coherence can reverse the course of energy transfer, allowing flow of energy from the metallic nanoparticle to the quantum dot. We also explore the susceptibility of the metal nanoparticle and show that it is strongly influenced by the presence of the quantum dot.
我们研究了由半导体量子点和与弱探测电磁场相互作用的球形金属纳米粒子组成的混合系统中的光学效应。我们使用改进的非线性密度矩阵方程来描述系统的光学性质，并得到了量子点、金属纳米粒子和整个系统的线性极化率的封闭形式表达式。然后，我们研究了极化率对粒子间距离以及混合系统的材料参数的依赖性。我们发现，量子点的极化率在特定频率下表现出光学透明性。此外，我们表明，在施加场的一定频率范围内，半导体量子点的极化率导致增益。这表明在这样的混合系统中，量子相干性可以反转能量转移的过程，允许能量从金属纳米粒子流向量子点。我们还研究了金属纳米粒子的极化率，并表明它受到量子点的强烈影响。
