Polariton chemistry has emerged in roughly the last decade as a new way of using light to control chemical reactions as well as other properties and processes involving atoms and molecules. It has been a delight to experimentalists and to theorists alike to see this field grow new interfaces between chemistry, physics, optics, nanofabrication, materials science and engineering, and more. While the field has been motivated by potential applications—the potential to achieve unprecedented selectivity and efficiency in chemical transformations, access to new chemical products, possible ways to reimagine catalysis, and realizing new platforms for quantum information—it has also been motivated by the beautiful ideas, theories, and phenomenology that have captured the imagination of researchers.

The authors find this particularly appealing, as the field necessitates the marriage between two things they find deeply fascinating—the (quantum) theory of light and of matter—in this case, cavity quantum electrodynamics and molecular quantum mechanics (CQED). They also have found it both challenging and rewarding to deepen their knowledge and understanding of these two theories, and as a group primarily composed of chemists, this work has often required them to grapple with the fact that there exist very few introductory resources aimed at chemists that cover CQED. The concepts and formalism of CQED are not part of the lingua franca of physical chemistry courses at the undergraduate level for sure, and rarely at the graduate level.

The authors’ main motivation for this digital primer was to create a resource that could introduce these concepts in language that is familiar to chemists, and within a context that chemists can appreciate. They also wanted to provide working code, implementing several different models and comparing their results; the authors believe the implementation can be quite complementary to the formalism and can help build intuition about them more quickly. In principle, it can also give students a jump-start to performing real calculations and simulations. To that end, students are encouraged to work through the manipulations actively and to attempt to implement their own versions of the code.