Molecular polaritons, the hybridization of electronic states in molecules with photonic excitation inside a cavity, play an important role in fundamental quantum science and technology. Understanding the decoherence mechanism of molecular polaritons is among the most significant fundamental questions. We theoretically demonstrate that hybridizing many molecular excitons in a cavity protects the overall quantum coherence from phonon-induced decoherence. The polariton coherence time can be prolonged up to 100 fs with a realistic collective Rabi splitting and quality factor at room temperature, compared to the typical electronic coherence time which is around 15 fs. Our numerically exact simulations and analytic theory suggest that the dominant decoherence mechanism is the population transfer from the upper polariton state to the dark state manifold. Increasing the collective coupling strength will increase the energy gap between these two sets of states and thus prolong the coherence lifetime. We further derived valuable scaling relations that directly indicate how polariton coherence depends on the number of molecules, Rabi splittings, and light–matter detunings.

中文翻译：

---

集体光-物质耦合状态下分子极化激元退相干的机制


分子极化激元是分子中电子态与腔内光子激发的杂化，在基础量子科学和技术中发挥着重要作用。了解分子极化激元的退相干机制是最重要的基本问题之一。我们从理论上证明，在一个腔中杂化许多分子激子可以保护整体量子相干性免受声子诱导的退相干性的影响。与典型的电子相干时间约为 15 fs 相比，在室温下具有真实的集体 Rabi 分裂和品质因数，极化激元相干时间可以延长至 100 fs。我们的数值精确模拟和分析理论表明，主要的退相干机制是从上极化子态到暗态流形的种群转移。增加集体耦合强度将增加这两组状态之间的能量间隙，从而延长相干寿命。我们进一步推导出有价值的缩放关系，这些关系直接表明极化子相干性如何取决于分子数量、Rabi 分裂和光物质分离。