EPFL researchers, working at the boundary between classical and quantum physics, have developed a method for quickly spotting molecules with particularly interesting electron properties.

Credit: EPFL/LCPT

In isolated atoms, the oscillations of electron density are regular, but in most polyatomic molecules, the oscillations quickly become damped. This process is known as decoherence. However, in some molecules the oscillations last longer before decoherence sets in. The EPFL researchers developed a method which captures the physical mechanism behind decoherence, which consequently enables them to identify molecules with long-lasting coherences. Their method could prove interesting in the development of new electron-based technology or studying quantum effects in biomolecules. The findings were recently published in Physical Review Letters.

"Electron movement takes place extremely rapidly—on an attosecond scale—so it's very difficult to observe," says Nikolay Golubev, a post-doc at LCPT and the study's lead author. Furthermore, electron motion is strongly coupled to other processes in a molecule. This is why the research team incorporated additional piece of information into their study: the slower dynamics of the atomic nuclei and its influence on that of electrons. It was found that in most molecular structures the slow nuclear rearrangement damps the initially coherent oscillations of electrons and makes them disappear in a few femtoseconds.