Direct observation of geometric phase in dynamics around a conical intersection

TL;DR

This paper reports the first direct observation of geometric-phase interference in molecular dynamics around a conical intersection, using a trapped-ion quantum simulator to reconstruct wavepacket densities.

Contribution

It demonstrates a novel experimental technique to observe geometric phases directly and validates the use of trapped-ion simulators for nuclear quantum effect studies.

Findings

Successful reconstruction of 2D wavepacket densities.

Agreement between experimental results and theoretical models.

Validation of trapped-ion quantum simulators for quantum chemical phenomena.

Abstract

Conical intersections are ubiquitous in chemistry and physics, often governing processes such as light harvesting, vision, photocatalysis, and chemical reactivity. They act as funnels between electronic states of molecules, allowing rapid and efficient relaxation during chemical dynamics. In addition, when a reaction path encircles a conical intersection, the molecular wavefunction experiences a geometric phase, which can affect the outcome of the reaction through quantum-mechanical interference. Past experiments have measured indirect signatures of geometric phases in scattering patterns and spectroscopic observables, but there has been no direct observation of the underlying wavepacket interference. Here, we experimentally observe geometric-phase interference in the dynamics of a wavepacket travelling around an engineered conical intersection in a programmable trapped-ion quantum simulator. To achieve this, we develop a technique to reconstruct the two-dimensional wavepacket densities of a trapped ion. Experiments agree with the theoretical model, demonstrating the ability of analog quantum simulators -- such as those realised using trapped ions -- to accurately describe nuclear quantum effects.