Researchers at Duke University have used a quantum-based method to investigate a curious quantum effect known as a “conical intersection.” This effect influences how light-absorbing molecules interact with incoming photons. Conical intersections have significant implications for various processes like photosynthesis, vision, and photocatalysis. The researchers harnessed a quantum simulator derived from quantum computing research to address this long-standing question in chemistry. This demonstrates how advancements in quantum computing can aid in exploring fundamental scientific phenomena.

A conical intersection is like a mountain peak that touches its reflection from above and plays a crucial role in electron motion between energy states. When a molecule absorbs energy from incoming light, its atoms begin rearranging themselves to accommodate the excited electrons, and this rearrangement occurs at the conical intersection. However, because atoms and electrons move rapidly in a quantum fashion, the molecule exists in multiple shapes simultaneously. Certain molecular transformations are hindered due to a mathematical quirk called a “geometric phase,” making the molecule unable to reach a specific shape.

Measuring this quantum effect has been historically challenging due to its brief existence (in femtoseconds) and minuscule scale (atoms). In this study, the researchers used a five-ion quantum computer to measure the geometric phase in action directly. The results revealed that specific configurations on one side of the conical intersection failed to transition to the other side despite no energy barrier. This research showcases how even basic quantum computers can model and unveil the inner workings of complex quantum systems, providing valuable insights into the world of quantum chemistry.

In parallel, a separate experiment at the University of Sydney also observed the geometric phase using an ion trap quantum simulator, reinforcing the consistency of these findings. Overall, this work highlights the potential of quantum computing and simulators in advancing our understanding of fundamental quantum phenomena.

Reference:

Whitlow, J., Jia, Z., Wang, Y., Fang, C., Kim, J., & Brown, K. R. (2023). Quantum simulation of conical intersections using trapped ions. Nature Chemistry. https://doi.org/10.1038/s41557-023-01303-0