Centre for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
J Chem Phys. 2012 Jun 14;136(22):224507. doi: 10.1063/1.4719210.
Based on the generating function formalism, we investigate broadband photon statistics of emission for single dimers and trimers driven by a continuous monochromatic laser field. In particular, we study the first and second moments of the emission statistics, which are the fluorescence excitation line shape and Mandel's Q parameter. Numerical results for this line shape and the Q parameter versus laser frequency in the limit of long measurement times are obtained. We show that in the limit of small Rabi frequencies and laser frequencies close to resonance with one of the one-exciton states, the results for the line shape and Q parameter reduce to those of a two-level monomer. For laser frequencies halfway the transition frequency of a two-exciton state, the photon bunching effect associated with two-photon absorption processes is observed. This super-Poissonian peak is characterized in terms of the ratio between the two-photon absorption line shape and the underlying two-level monomer line shapes. Upon increasing the Rabi frequency, the Q parameter shows a transition from super- to sub- to super-Poissonian statistics. Results of broadband photon statistics are also discussed in the context of a transition (frequency) resolved photon detection scheme, photon tracking, which provides a greater insight in the different physical processes that occur in the multi-level systems.
基于产生函数形式理论，我们研究了在连续单色激光场驱动下单二聚体和三聚体的宽带光子统计。特别地，我们研究了发射统计的第一和第二矩，即荧光激发线形状和曼德尔 Q 参数。在长测量时间的极限下，我们得到了这个线形状和 Q 参数与激光频率的数值结果。我们表明，在小拉比频率和激光频率接近一个单激子态的共振的极限下，线形状和 Q 参数的结果简化为两能级单体的结果。对于激光频率位于两个激子态的跃迁频率的一半处，与双光子吸收过程相关的光子聚束效应被观察到。这个超泊松峰可以用双光子吸收线形状与基础两能级单体线形状的比值来描述。随着拉比频率的增加，Q 参数显示出从超泊松到亚泊松再到超泊松统计的转变。宽带光子统计的结果也在过渡（频率）分辨光子探测方案，即光子跟踪的背景下进行了讨论，它为多能级系统中发生的不同物理过程提供了更深入的了解。
