Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
J Chem Phys. 2011 Mar 7;134(9):094114. doi: 10.1063/1.3556706.
We derive the Bloch equations for a two-level system coupled to a spin bath of infinitely many two-level atoms to examine phase and energy relaxation of an optically excited system. We show that increasing temperature assists coherence. This is reflected in a number of anomalous features of relaxation of the system, e.g., decrease of integrated absorption coefficient with temperature, nonlinear variation of linewidth with incident power. We also predict that thermally induced coherence may result in anomalous narrowing of linewidth, reminiscent (but distinct) of "motional narrowing" of spectral line. The theoretical results are discussed in the light of absorption-emission experiments on single quantum dots.
我们推导出与无限多个双能级原子自旋池耦合的双能级系统的 Bloch 方程，以研究光激发系统的相位和能量弛豫。我们表明，温度升高有助于相干性。这反映在系统弛豫的许多异常特征中，例如，随着温度的升高，积分吸收系数的降低，线宽与入射功率的非线性变化。我们还预测，热诱导的相干性可能导致线宽的异常变窄，这让人联想到（但又不同）光谱线的“动力变窄”。理论结果结合单量子点的吸收-发射实验进行了讨论。
