Superradiance and Dipole Ordering of an N Two-Level System Interacting with Optical Near Fields
Superradiance and Dipole Ordering of an N Two-Level System Interacting with Optical Near Fields
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与光学近场相互作用的 N 两能级系统的超辐射度和偶极子排序
DOI：
10.1143/jpsj.72.2984
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发表时间：
2003
影响因子：
1.7
通讯作者：
M. Ohtsu
中科院分区：
文献类型：
--
作者：
A. Shojiguchi;Kiyoshi Kobayashi;S. Sangu;K. Kitahara;M. Ohtsu
提出了一个N个两能级激子通过局域光子表示的光学近场相互作用的模型。在低激子密度极限下，任何两个能级之间的偶极矩或量子相干性的量子动力学是线性的。随着激子密度的增大，系统动力学变得非线性，系统存在多种偶极分布的准稳态，这取决于系统参数。这些准稳态是在有效哈密顿量的帮助下分类的，有效哈密顿量是从用幺正变换对定域光子的自由度进行重整化得到的。其中有一个“铁磁”状态（偶极有序状态），其中所有的电偶极子都在同一方向上排列，还有一个“反铁磁”状态，其中所有的偶极子交替改变方向。此外，我们还证明了通过适当地改变粒子数分布的初始值，任意的态都可以转变为偶极有序态。例如，如果我们最初准备了一个偶极禁戒态，它类似于“反铁磁”态，并且不能与传播的远场耦合，如果我们适当地操纵粒子数分布，初始态就会演变成偶极有序态。详细研究了这种偶极有序态的辐射性质。在忽略辐射能量耗散的情况下，我们发现某些有序态具有与迪凯超辐射相当的强辐射。然后通过引入辐射库，导出了耗散主方程。在有和没有量子相关的情况下求解方程，我们用数值方法表明，辐射谱中的多峰在这两种情况下都可以存在。讨论了这一现象的机理，并简要评述了其在纳米尺度光子器件中的应用。
A model is presented for a system of N two-level excitons interacting with each other via optical nearfields represented as localized photons. In a low exciton density limit, quantum dynamics of the dipolemoments or quantum coherence between any two energy levels is linear. As the exciton density becomeshigher, the dynamics becomes nonlinear, and the system has several kinds of quasi-steady states of thedipole distribution depending on the system parameters. These quasi-steady states are classified with thehelp of the effective Hamiltonian that is derived from the renormalization of degrees of freedom oflocalized photons with a unitary transformation. Among them there exist a ‘‘ferromagnetic’’ state(dipole-ordered state), in which all electric dipoles are aligned in the same direction, and an ‘‘anti-ferromagnetic’’ state, where all dipoles alternatingly change the direction. In addition, we show that anarbitrary state can be transformed into a dipole-ordered state by manipulating initial values of thepopulation differences appropriately. For example, if we initially prepare a dipole-forbidden state, whichis similar to the ‘‘anti-ferromagnetic’’ state and cannot be coupled with propagating far fields, and if wemanipulate the distribution of the population differences properly, the initial state evolves into a dipole-ordered state. The radiation property of such dipole-ordered states is examined in detail. Neglectingenergy dissipation by radiation, we find that some of the ordered states show strong radiation equivalentto Dicke’s superradiance. Then by introducing a radiation reservoir, the dissipative master equation isderived. Solving the equation with and without quantum correlations, we numerically show that multiplepeaks in the radiation profile can survive in both cases. The mechanism of this phenomenon is discussed,and a brief comment on an application to photonic devices on a nanometer scale is given.
DOI：
10.1109/jstqe.2002.801738
发表时间：
2002-07-01
影响因子：
4.9
作者：
Ohtsu, M;Kobayashi, K;Yatsui, T
通讯作者：
Yatsui, T