Remote control of chemistry in optical cavities

Manipulation of chemical reactivity often involves changing reagents or environmental conditions. Alternatively, strong coupling between light and matter offers a way to tunably hybridize their physicochemical properties and thereby change reaction dynamics without synthetic modifications to the starting material. Here, we theoretically design a polaritonic (hybrid photonic-molecular) device that supports ultrafast tuning of reaction yields even when the catalyst and its reactant are spatially separated across several optical wavelengths. We demonstrate how photoexcitation of a `remote catalyst' in an optical microcavity can control photochemistry of a reactant in another microcavity. Harnessing delocalization across the spatially separated compounds that arises from strong cavity-molecule coupling, this intriguing phenomenon is shown for the infrared-induced \textit{cis} $\rightarrow$ \textit{trans} conformational isomerization of nitrous acid (HONO). Indeed, increasing the excited-state population of the remote catalyst can enhance the isomerization efficiency by an order of magnitude. The theoretical proposal reported herein is generalizable to other reactions and thus introduces a versatile tool to control photochemistry.