Molecular vibrational polaritons, hybrid quasi-particles formed by molecular vibrations and cavity photons through strong light–matter coupling, have attracted much attention due to their potential to alter photonic properties and to change the course of chemical reactions. The ultrafast dynamics of molecular vibrational polaritons have been studied to advance our understanding of these interesting hybrid quasiparticles. For example, the roles of dark states, hot vibrational mode relaxation in cavities, and manipulation of nonlinear polariton-polariton interactions have been investigated by ultrafast spectroscopy. However, the coherent nature of polaritons makes many viable quantum pathways able to contribute to ultrafast spectroscopic signals, such as two-dimensional infrared spectroscopy (2D IR), complicating its interpretation. Here, using a mid-IR pulse shaper, we report an experimental way to directly measure polariton nonlinear responses involving specific quantum pathways by eliminating others. For example, either coherence or population states may be exclusively probed. This work is useful for the development of polariton-based quantum technologies, and research into the role of coherence in energy transportation in artificial and natural energy materials, and cavity chemistry.

中文翻译：

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控制分子振动极化子中的量子途径

分子振动极化子，由分子振动和光子通过强光-质耦合形成的杂化准粒子，由于它们具有改变光子性质和改变化学反应过程的潜力而备受关注。研究了分子振动极化子的超快动力学，以增进我们对这些有趣的杂化准粒子的理解。例如，已经通过超快光谱研究了暗态，空腔中热振动模式弛豫以及非线性极化子-极化子相互作用的操纵的作用。但是，极化子的相干特性使许多可行的量子路径能够对超快光谱信号做出贡献，例如二维红外光谱（2D IR），这使其解释变得复杂。这里，使用中红外脉冲整形器，我们报告了一种通过消除其他方法直接测量涉及特定量子途径的极化子非线性响应的实验方法。例如，可以专门探究相干状态或总体状态。这项工作对于基于极化子的量子技术的发展，以及研究相干性在人造和天然能源材料中的能量传输以及腔化学中的作用非常有用。