The team wished to push the envelope further, hoping to squeeze together two single atoms using little more than “the aid of a photon”, as their study casually notes. So, using carefully directed lasers with atom-specific wavelengths – something the authors liken to using “optical tweezers” – these two atoms of sodium and cesium were set up on their groundbreaking date.
As well as bringing them together, the light source also energetically excited them, just enough to react and form a single sodium-cesium molecule, NaCs.
The final product was sadly ephemeral, partly because they were so “excited”. The next step will be to get those atoms to stick together for longer by not getting them so riled up in the first place – something easier said than done.
Still, this mastery of the miniature is more than just a start; this is a world first, and the implications are rather delightful.
Apart from demonstrating that this tiny collision can be both carefully managed and observed, the choice to use sodium and cesium to build a molecule wasn’t random: its properties make it a “strong candidate for a molecular qubit” (quantum bit), the smallest individual component of those ever-elusive quantum computers.
We're still a long way off from true "designer molecules" for quantum computers. Nevertheless, big things often have (atomically) small beginnings.