Photo-chemistry studies how light can control chemical reactions. Photo-chemistry lies at the heart of many different processes in our daily experience, ranging from vision to solar energy conversion. Over the past decades, increasingly sophisticated light sources, in particular lasers, have transformed this field by offering precise control over wavelength, intensity, and timing, enabling selective excitation of molecules and material and granting sophisticated manipulation methods of reaction pathways. A natural next step is to go beyond the use of light as a simple trigger, and instead engineer the landscape in which chemical processes occur. Optical cavities provide exactly this opportunity: by confining light between mirrors, they allow light-matter interactions to be reshaped at a fundamental level, even in the absence of applied illumination. In such cavities, quantum fluctuations of the electromagnetic vacuum are strongly enhanced and can act as a subtle catalytic agent, reshaping molecular energy landscapes and opening reaction pathways that are inaccessible under ordinary conditions.
While conventional chemistry typically involves complex environments and many uncontrolled variables, ultracold molecules inside optical cavities offer a clean and tunable platform. At ultralow temperatures, molecules can be prepared in well-defined quantum states, their interactions can be precisely engineered, and their dynamics directly observed. This level of control opens the door to a predictive, “designer” approach to chemistry, in which reaction outcomes can be steered through light-matter coupling rather than brute-force energy input.
In LIRICO, we want to combine ultracold molecules with cavity quantum electrodynamics to develop new techniques for controlling chemical reactions. The fulcrum of our strategy is to use high-finesse optical cavities to create hybrid light-matter states, known as molecular polaritons, enabling reactions to be enhanced, suppressed, or redirected by tuning the molecule-cavity coupling. We also want to study a peculiar type of chemical reaction, so-called isotope-exchange reaction, that has an extremely low reaction energy and allows us to investigate with quantum-state resolution the outcome of a reaction event. In this way, we can really pin down the parameter space where cavities can modify chemistry, with a precision that is unmatched by other platforms. The extreme experimental control of ultracold systems grants us a uniquely powerful testbed for exploring the fundamental limits of cavity-modified chemistry.
