X-ray four-wave mixing captures elusive electron interactions inside atoms and molecules

Scientists at the SwissFEL free-electron X-ray laser have achieved a long-standing experimental goal in physics: showing how electrons dance together. The technique, known as X-ray four-wave mixing, opens a new way of seeing how energy and information flow within atoms and molecules. In the future, this could shed light on how quantum information is stored and lost, contributing to the design of more error-tolerant quantum devices. The results are reported in Nature.