Using high-resolution lasers to test quantum electrodynamics

The precise measurement of atomic and molecular structure allows us to test state-of-the-art theories that are used to understand physical and chemical processes. We have developed a unique laser-based spectroscopic system to perform extremely high-resolution measurements of atoms and molecules in the vacuum-ultraviolet region. Our international research team will exploit this laser system's capabilities to help resolve a marked discrepancy between quantum-electrodynamic (QED) theory and previous precision measurements of the helium 1S - 2S two-photon transition frequency. We will measure this frequency with unprecedented precision to determine the Lamb shift of the helium 1S ground state - a QED quantity of fundamental significance.