Predicted state of atomic collapse seen for first time - MIT News Office

Predicted state of atomic collapse seen for first time - MIT News Office: What the new Science paper reports is that atoms sitting on a sheet of graphene — a two-dimensional structure composed of carbon atoms linked in a chicken-wire-like mesh of hexagonal bonds — exactly mimic the properties of atomic nuclei, and can be manipulated to recreate and observe complex atomic phenomena. The key is that while electrons move through graphene as relativistic particles — as though they were massless, even though they actually do have mass — their motion is 300 times slower than that of true massless particles. As a result, the expected phenomenon of collapse should take place at one-three-hundredth the normal nuclear charge — putting it well within reach of experimental observations.

To simulate atomic nuclei, the researchers used pairs of calcium atoms on the graphene surface; they were able to manipulate these pairs (called dimers) on the surface using the probe tip of a scanning tunneling microscope. As soon as three dimers were pushed close together, the surrounding field of electrons showed a specific spectrum of resonances that precisely matched the decades-old predictions of atomic collapse. The observed resonances persisted in a four-dimer and five-dimer artificial nucleus.