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1. Collective Vibrational Strong Coupling Effects on Molecular Vibrational Relaxation and Energy Transfer: Numerical Insights via Cavity Molecular Dynamics Simulations**

   https://doi.org/10.1002/anie.202103920  

   Li, Tao E. ; Nitzan, Abraham ; Subotnik, Joseph E. ( July 2021 , Angewandte Chemie International Edition)

   For a small fraction of hot CO₂molecules immersed in a liquid‐phase CO₂thermal bath, classical cavity molecular dynamics simulations show that forming collective vibrational strong coupling (VSC) between the C=O asymmetric stretch of CO₂molecules and a cavity mode accelerates hot‐molecule relaxation. This acceleration stems from the fact that polaritons can be transiently excited during the nonequilibrium process, which facilitates intermolecular vibrational energy transfer. The VSC effects on these rates 1) resonantly depend on the cavity mode detuning, 2) cooperatively depend on Rabi splitting, and 3) collectively scale with the number of hot molecules. For larger cavity volumes, the average VSC effect per molecule can remain meaningful for up toN≈10⁴molecules forming VSC. Moreover, the transiently excited lower polariton prefers to relax by transferring its energy to the tail of the molecular energy distribution rather than distributing it equally to all thermal molecules. As far as the parameter dependence is concerned, the vibrational relaxation data presented here appear analogous to VSC catalysis in Fabry–Pérot microcavities.

    

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2. Collective Vibrational Strong Coupling Effects on Molecular Vibrational Relaxation and Energy Transfer: Numerical Insights via Cavity Molecular Dynamics Simulations**

   https://doi.org/10.1002/ange.202103920  

   Li, Tao E. ; Nitzan, Abraham ; Subotnik, Joseph E. ( July 2021 , Angewandte Chemie)

   For a small fraction of hot CO₂molecules immersed in a liquid‐phase CO₂thermal bath, classical cavity molecular dynamics simulations show that forming collective vibrational strong coupling (VSC) between the C=O asymmetric stretch of CO₂molecules and a cavity mode accelerates hot‐molecule relaxation. This acceleration stems from the fact that polaritons can be transiently excited during the nonequilibrium process, which facilitates intermolecular vibrational energy transfer. The VSC effects on these rates 1) resonantly depend on the cavity mode detuning, 2) cooperatively depend on Rabi splitting, and 3) collectively scale with the number of hot molecules. For larger cavity volumes, the average VSC effect per molecule can remain meaningful for up toN≈10⁴molecules forming VSC. Moreover, the transiently excited lower polariton prefers to relax by transferring its energy to the tail of the molecular energy distribution rather than distributing it equally to all thermal molecules. As far as the parameter dependence is concerned, the vibrational relaxation data presented here appear analogous to VSC catalysis in Fabry–Pérot microcavities.

    

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3. Ultrafast Coherence Delocalization in Real Space Simulated by Polaritons

   https://doi.org/10.1002/adom.202102237  

   Xiang, Bo ; Yang, Zimo ; You, Yi‐Zhuang ; Xiong, Wei ( January 2022 , Advanced Optical Materials)

   Coherence delocalization has been investigated on a coupled‐cavity molecular polariton platform in time, frequency, and spatial domains, enabled by ultrafast two‐dimensional infrared hyperspectral imaging. Unidirectional coherence delocalization (coherence prepared in one cavity transferred to another cavity) has been observed in frequency and real space. This directionality is enabled by the dissipation of delocalized photon from high‐energy to low‐energy modes, described by Lindblad dynamics. Further experiments show that when coherences are directly prepared between polaritons from different cavities, only energetically nearby polaritons can form coherences that survive the long‐range environmental fluctuation. Together with the Lindblad dynamics, this result implies that coherences delocalize through a one‐step mechanism where photons transfer from one cavity to another, shedding light to coherence evolution in natural and artificial quantum systems. This new optical platform based on molecular vibrational polariton thus demonstrates a way of combining photon and molecular modes to simulate coherence dynamics in the infrared regime.

    

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4. Resonant catalysis of thermally activated chemical reactions with vibrational polaritons

   https://doi.org/10.1038/s41467-019-12636-1  

   Campos-Gonzalez-Angulo, Jorge A. ; Ribeiro, Raphael F. ; Yuen-Zhou, Joel ( October 2019 , Nature Communications)

   Interaction between light and matter results in new quantum states whose energetics can modify chemical kinetics. In the regime of ensemble vibrational strong coupling (VSC), a macroscopic number$$N$$$N$of molecular transitions couple to each resonant cavity mode, yielding two hybrid light–matter (polariton) modes and a reservoir of$$N-1$$$N-1$dark states whose chemical dynamics are essentially those of the bare molecules. This fact is seemingly in opposition to the recently reported modification of thermally activated ground electronic state reactions under VSC. Here we provide a VSC Marcus–Levich–Jortner electron transfer model that potentially addresses this paradox: although entropy favors the transit through dark-state channels, the chemical kinetics can be dictated by a few polaritonic channels with smaller activation energies. The effects of catalytic VSC are maximal at light–matter resonance, in agreement with experimental observations.

    

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5. Collective Vibrational Strong Coupling Effects on Molecular Vibrational Relaxation and Energy Transfer: Numerical Insights via Cavity Molecular Dynamics Simulations

   Li, T.E. Li ; Nitzan, A. ; Subotnik, J.E. ( May 2021 , Angewandte Chemie)

   null (Ed.)

   We use classical cavity molecular dynamics simulations to investigate the effect of optical cavity environment on vibrational energy transfer and relaxation. For a small fraction of vibrationally hot CO2 molecules immersed in a liquid-phase CO2 thermal bath, in a cavity that supports a cavity mode in resonance with the CO asymmetric stretch vibration, forming collective vibrational strong coupling (VSC) and a cavity mode accelerates hot molecule relaxation. This acceleration stems from the fact that polaritons can be transiently excited during the nonequilibrium process, which facilitates intermolecular vibrational energy transfer. The VSC effects on these rates (i) resonantly depend on the cavity mode detuning, (ii) cooperatively depend on Rabi splitting, and (iii) collectively scale with the number of hot molecules. This behavior weakens with increasing cavity size (at constant molecular density), that is, constant Rabi splitting) but remains meaningful up to cavities containing 10^4 molecules 

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