Designing composite quantum systems using trapped-ion quantum computers: a case study in vibronic energy transfer

Studying molecular vibronic interactions, where vibrational and electronic degrees of freedom are coupled, is a key step toward practical computational design of molecular systems relevant to artificial light harvesting, molecular energy transfer, and bio-imaging. However, modelling vibrational degrees of freedom requires increasingly large Hilbert spaces, resulting in a problem that is difficult to solve classically. Here, we use a trapped-ion quantum computer to overcome this complexity and simulate interactions between molecular clusters. Importantly, we avoid simulating low-level electrons and nuclei, and instead consider only the "sub-system" level of single molecules as our building blocks. To this end, we use chemical laboratory data to learn the parameters for a single molecular sub-system then use them to simulate the dynamics of molecular clusters under the Holstein Hamiltonian.