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. Theory predicts that the conical intersection will result in a geometric phase for a wavepacket on the ground potential energy surface, and although conical intersections have been observed experimentally, the geometric phase has not been directly observed in a molecular system. Here we use a trapped atomic ion system to perform a quantum simulation of a conical intersection. The ion's internal state serves as the electronic state, and the motion of the atomic nuclei is encoded into the motion of the ions. The simulated electronic potential is constructed by applying state-dependent optical forces to the ion. We experimentally observe a clear manifestation of the geometric phase using adiabatic state preparation followed by motional state measurement. Our experiment shows the advantage of combining spin and motion degrees for quantum simulation of chemical reactions. Geometric phase interference has been predicted to appear around conical intersections but has been experimentally illusive owing to competing effects in molecular systems. Now, this effect has been demonstrated in chains of trapped ions using state-of-the-art quantum simulation and read-out techniques.

Automated summary

This article presents a quantum simulation of conical intersections using a trapped atomic ion system, and experimentally observes the manifestation of geometric phase, demonstrating the advantage of combining spin and motion for quantum simulation of chemical reactions.