The technique focuses on the photoelectric effect, where high-energy light causes electrons to detach from atoms. Traditionally, these emitted electrons (photoelectrons) are treated as classical particles. However, they are quantum objects, behaving as both particles and waves, requiring quantum mechanical descriptions.
"By measuring the quantum state of the photoelectron, our technique can precisely address the question of 'how quantum is the electron'," explains David Busto, associate senior lecturer in atomic physics. The process involves ionizing atoms with ultrashort, high-energy light pulses and using laser pulses of different colors to reconstruct the quantum state slice by slice, similar to CT scans.
The KRAKEN technique has been successfully applied to helium and argon atoms, revealing that the photoelectron quantum state varies depending on the material. This advancement expands the potential of photoelectron spectroscopy, a field recognized with a Nobel Prize in 1981. It provides access to previously unavailable quantum information.
Potential applications include studying molecular gases, liquids, and solids to understand how ionized targets react after electron loss. This could impact atmospheric photochemistry, light-harvesting systems like solar cells, and photosynthesis. It also bridges attosecond science and spectroscopy with quantum information and technology, contributing to the ongoing second quantum revolution. This revolution aims to manipulate individual quantum objects for various applications, potentially leading to advancements in material science and quantum technologies.