Modeling noncovalent interatomic interactions on a photonic quantum computer

Noncovalent interactions are a key ingredient to determine the structure, stability, and dynamics of materials, molecules, and biological complexes. However, accurately capturing these interactions is a complex quantum many-body problem, with no efficient solution available on classical computers. A widely used model to accurately and efficiently model noncovalent interactions is the Coulomb-coupled quantum Drude oscillator (cQDO) many-body Hamiltonian, for which no exact solution is known. We show that the cQDO model lends itself naturally to simulation on a photonic quantum computer, and we calculate the binding energy curve of diatomic systems by leveraging Xanadu's strawberry fields photonics library. Our study substantially extends the applicability of quantum computing to atomistic modeling by showing a proof-of-concept application to noncovalent interactions, beyond the standard electronic-structure problem of small molecules. Remarkably, we find that two coupled bosonic QDOs exhibit a stable bond. In addition, our study suggests efficient functional forms for cQDO wave functions that can be optimized on classical computers, and capture the bonded-to-noncovalent transition for increasing interatomic distances.