Lindblad theory of dynamical decoherence of quantum-dot excitons
Lindblad theory of dynamical decoherence of quantum-dot excitons
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DOI：
10.1103/physrevb.87.195306
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发表时间：
2013-05-15
影响因子：
3.7
通讯作者：
Keeling, J.
中科院分区：
文献类型：
--
作者：
Eastham, P. R.;Spracklen, A. O.;Keeling, J.
我们使用 Bloch-Redfield-Wangsness 理论来计算相干控制实验中声声子的影响，其中量子点激子由整形激光脉冲驱动。该理论产生了点的密度算子的广义 Lindblad 方程，具有由于瞬时修饰态之间的声子跃迁而导致的时间相关阻尼和退相干。它捕获了与最近应用于拉比振荡实验的形式类似的物理现象 [Ramsay 等人，Phys.莱特牧师。 104, 017402 (2010)] 但保证了密度算子的正性。在足够低的温度下，它给出的结果相当于完全非马尔可夫方法的结果 [Luker et al., Phys. Rev. B 85, 121302 (2012)]，但模拟起来要简单得多。讨论了该理论的几个应用。我们将其应用于绝热快速通过实验，并展示了如何对脉冲进行整形，以最大限度地提高使用扫频激光脉冲产生单个激子的概率。我们还利用该理论提出并分析了通过实验确定声子态密度的方法，即声子谱，通过探索有效阻尼率对驱动场的依赖性。
We use the Bloch-Redfield-Wangsness theory to calculate the effects of acoustic phonons in coherent control experiments where quantum-dot excitons are driven by shaped laser pulses. This theory yields a generalized Lindblad equation for the density operator of the dot, with time-dependent damping and decoherence due to phonon transitions between the instantaneous dressed states. It captures similar physics to the form recently applied to Rabi oscillation experiments [Ramsay et al., Phys. Rev. Lett. 104, 017402 (2010)] but guarantees positivity of the density operator. At sufficiently low temperatures, it gives results equivalent to those of fully non-Markovian approaches [Luker et al., Phys. Rev. B 85, 121302 (2012)] but is significantly simpler to simulate. Several applications of this theory are discussed. We apply it to adiabatic rapid passage experiments and show how the pulses can be shaped to maximize the probability of creating a single exciton using a frequency-swept laser pulse. We also use this theory to propose and analyze methods to determine the phonon density of states experimentally, i.e., phonon spectroscopy, by exploring the dependence of the effective damping rates on the driving field.