Quantum simulation of conical intersections using trapped ions.*

Conical intersections often control the reaction products of photochemical processes and occur when two electronic potential energy surfaces intersect [1]. Theory predicts that the conical intersection will result in a geometric phase for a wavepacket on the ground potential energy surface [2], and although conical intersections have been observed experimentally, the geometric phase has not been directly observed in a molecular system. In this presentation, I discuss results and methods from recent work [3] where we used a trapped atomic ion system to perform a quantum simulation of a conical intersection. The ion’s internal state served as the electronic state, and the motion of the atomic nuclei was encoded into the motion of the ions. The simulated electronic potential was constructed by applying state-dependent optical forces to the ion. We experimentally observed a clear manifestation of the geometric phase using adiabatic state preparation followed by motional state measurement. 

[1] Yarkony, David R. "Diabolical conical intersections." Reviews of Modern Physics 68.4 (1996): 985.

[2] Berry, Michael Victor. "Quantal phase factors accompanying adiabatic changes." Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences 392.1802 (1984): 45-57.

[3] Whitlow, Jacob, Zhubing Jia, Ye Wang, Chao Fang, Jungsang Kim, and Kenneth R. Brown. "Quantum simulation of conical intersections using trapped ions." Nature Chemistry (2023): 1-6.