Quantum simulation of chemical dynamics on a trapped-ion quantum computer*

Simulating the dynamics of quantum chemical systems is a promising application of quantum computers. While most quantum algorithms and experimental demonstrations have focused on calculations of electronic structure in molecules, a recently developed protocol [1] has proposed techniques to simulate nuclear dynamics as well. Expanding upon this protocol, we map the quantum nuclear Hamiltonian of a shared proton in 2,2'-bipyridine directly onto quantum gates that can be implemented on an ion-trap quantum computer. Exploiting underlying structures in the nuclear Hamiltonian, we reduce the number of required quantum gates to a level achievable by current NISQ-era devices. Finally, we implement our quantum circuit on IonQ's 11-qubit trapped-ion quantum processor, where the nuclear time-evolution operator is translated into an exact decomposition of quantum gates. We observe the full time dynamics of the nuclear wavepacket evolution in two dimensions, which enables us to extract its characteristic vibrational frequencies, and ultimately its complete energy eigenspectrum. Our approach offers a new paradigm for simulating quantum chemical dynamics problems using NISQ-era devices.

D. Saha et al, J. Chem. Theory Comput. 17, 6713 (2021)