Trapped-Ion Quantum Simulation of Chemical Dynamics beyond Born-Oppenheimer

Understanding how molecular vibrations affect charge and energy transfer in complex chemical and biological systems requires modeling the interactions among the electronic, spin, and vibrational degrees of freedom, which cannot be treated independently, especially when the Born-Oppenheimer approximation breaks down. Trapped-Ion analog quantum simulation of out-of-equilibrium chemical dynamics can offer an alternative route to investigate these phenomena. I will show how trapped‑ion platforms, renowned for the coherence and programmability of multiple atomic states and motional degrees of freedom, can map natively onto vibrationally-assisted charge‑transfer models by tailoring Hamiltonian interactions between the ions’ native spin and bosonic degrees of freedom and by tuning their dissipative properties. Building on our recent simulation of a paradigmatic electron‑transfer model coupled to a single damped bosonic mode, I will introduce three layers of added complexity: (1) I will report on our recent experimental realization of excitation transfer dynamics with two engineered bosonic modes, exposing transfer characteristics absent in the single‑mode limit. In a two-site donor–acceptor system coupled to an Ohmic bath, we track non-equilibrium transfer rates as functions of mode degeneracy and vibronic‑coupling strength, highlighting the role of constructive interference of vibrational pathways in determining the transfer rate. (2) I will report on a new technique to independently tune the temperature of the bath and the dissipation rate. (3) I will cover a theoretical investigation of a Frenkel‑exciton model in which long-range interacting qubits are coupled to a damped collective phonon mode, capturing excitation dynamics in donor–acceptor assemblies that mimic the internal substructure of natural light‑harvesting complexes. These advances pave the way for using programmable spin-boson quantum systems for dissipative state engineering and simulating singlet fission processes in organic semiconductors.