AI 中文总结
研究腔耦合分子系综中电子极化激元离域，用无序Tavis-Cummings模型，发现能量无序会致集体分子特性丧失，通过相关函数量化转变，给出无损及非厄米模型下极化激元离域定量标准，强调评估时要综合考虑无序、耗散和集体耦合。
AI 中文摘要
分子极化激元是光与物质的混合准粒子，其集体特性常与跨越多个发射体的分子激发相关。然而，分子系综本质上是无序和耗散的，光谱上可见的极化激元峰不一定意味着分子特性是离域的。本文从理论上研究了静态能量无序以及有限的腔和分子线宽如何影响腔耦合分子系综中电子极化激元的离域。使用无序的Tavis-Cummings模型表明，能量无序会将极化激元态与暗态流形混合，即使极化激元光谱特征仍然可见，也会导致集体分子特性迅速丧失。用分子参与率、基于密度矩阵的相干度量和能量分辨自相关函数对这种转变进行了量化。在无损电子模型中，要保留扩展的极化激元分子成分，集体拉比分裂需超过无序宽度五倍以上，这比传统光谱强耦合条件更严格。将分析扩展到非厄米哈密顿量表明，腔-分子线宽不平衡会进一步降低对无序的容忍度。由此产生的离域边界表明，要保留扩展的分子极化激元成分，集体拉比分裂需大于约八倍的无序宽度加上约两倍的腔-分子线宽失配。这些结果为无序和损耗下极化激元离域提供了定量标准，表明在评估分子极化激元在实际光学腔中是否仍保持集体扩展时，必须综合考虑无序、耗散和集体耦合。
英文摘要
Molecular polaritons are hybrid light--matter quasiparticles whose collective character is often associated with molecular excitations extending over many emitters. However, molecular ensembles are intrinsically disordered and dissipative, and spectrally visible polariton peaks do not necessarily imply delocalized molecular character. Here, we theoretically examine how static energetic disorder and finite cavity and molecular linewidths affect the delocalization of electronic polaritons in cavity--coupled molecular ensembles. Using a disordered Tavis--Cummings model, we show that energetic disorder mixes polariton states with the dark-state manifold, causing a rapid loss of collective molecular character even when polaritonic spectral features remain visible. We quantify this crossover using the molecular participation ratio, a density--matrix--based coherence measure, and an energy--resolved autocorrelation function. In the lossless electronic model, preserving an extended polaritonic molecular component requires the collective Rabi splitting to exceed the disorder width by more than a factor of five, providing a stricter condition than conventional spectroscopic strong coupling. Extending the analysis to a non--Hermitian Hamiltonian shows that cavity--molecule linewidth imbalance further reduces disorder tolerance. The resulting delocalization boundary indicates that preserving an extended molecular polariton component requires a collective Rabi splitting larger than roughly eight times the disorder width plus approximately twice the cavity--molecule linewidth mismatch. These results provide a quantitative criterion for polariton delocalization under disorder and loss and show that disorder, dissipation, and collective coupling must be considered together when assessing whether molecular polaritons remain collectively extended in realistic optical cavities.
