Molecular vibrational polaritons (MVPs), formed by the hybridization of molecular vibrational modes and cavity modes, offer a promising avenue for quantum computing and chemical innovation. These hybrid states can influence chemical reaction rates, facilitate intermolecular energy transfer, and modify intramolecular vibrational energy distribution. Although the observed applications are promising, the underlying mechanisms remain unclear. Most polariton experiments are conducted under the collective regime, making a comprehensive understanding of polaritons from both quantum and classical perspectives essential.To investigate the quantum features and dynamics of polaritons, two-dimensional infrared (2D IR) spectroscopy was employed. By using modulated ultrafast laser pulses, we selectively excited the coherent signals of these polaritons while suppressing incoherent population dynamics within the polariton lifetime. This technique underscores the potential of polaritons as qubits. To enhance the system's robustness and complexity, we designed and fabricated innovative geometries on cavity mirrors, enabling lateral confinement within the cavity space and creating additional polariton modes. Our work demonstrates the potential to create new platforms for realizing cavity-based entangled photon sources and conducting entangled photon spectroscopies. Although vibrational strong coupling (VSC) is reported to alter thermally-activated chemical reactions, its mechanisms remain opaque. To address this, we examined the ultrafast dynamics of a simple unimolecular vibrational energy exchange in Fe(CO)5 under VSC beyond the polariton lifetime. This revealed two competing channels: pseudorotation and intramolecular vibrational-energy redistribution (IVR). We found that under polariton excitation, overall energy exchange was accelerated, with IVR becoming faster and pseudorotation slowing down. However, dark mode excitation showed unchanged dynamics compared to outside the cavity, with pseudorotation dominating. Thus, despite controversies regarding VSC-modified chemistry, our work demonstrates that VSC can indeed alter chemical reactions through the non-equilibrium preparation of polaritons.