Institut UTINAM, Univ. Bourgogne Franche-Comté, CNRS UMR 6213, 25030 Besançon Cedex, France.
Phys Rev E. 2018 Feb;97(2-1):022304. doi: 10.1103/PhysRevE.97.022304.
A tight-binding model is introduced for describing the dynamics of an exciton on an extended star graph whose central node is occupied by a trap. On this graph, the exciton dynamics is governed by two kinds of eigenstates: many eigenstates are associated with degenerate real eigenvalues insensitive to the trap, whereas three decaying eigenstates characterized by complex energies contribute to the trapping process. It is shown that the excitonic population absorbed by the trap depends on the size of the graph, only. By contrast, both the size parameters and the absorption rate control the dynamics of the trapping. When these parameters are judiciously chosen, the efficiency of the transfer is optimized resulting in the minimization of the absorption time. Analysis of the eigenstates reveals that such a feature arises around the superradiance transition. Moreover, depending on the size of the network, two situations are highlighted where the transport efficiency is either superoptimized or suboptimized.
本文引入了紧束缚模型来描述位于扩展星型图中央节点的陷阱上的激子动力学。在该图上，激子动力学由两种本征态控制：许多本征态与不依赖于陷阱的简并实特征值相关联，而由复能量特征的三个衰减本征态则有助于捕获过程。结果表明，被陷阱吸收的激子种群仅依赖于图形的大小。相比之下，图形的大小参数和吸收速率都控制着捕获的动力学。当这些参数被巧妙地选择时，转移效率被优化，从而使吸收时间最小化。本征态的分析表明，这种特性出现在超辐射跃迁附近。此外，根据网络的大小，突出了两种情况，其中传输效率要么被超优化，要么被次优化。
