Physicists at the University of Illinois recently announced they have discovered a new form of matter known as excitonium. Although theorized more than half a century ago, excitonium was only recently confirmed in experiments by the research team, which also included scientists from University of California at Berkeley, and University of Amsterdam. Excitonium is composed of a type of boson, a composite particle whose unique qualities enable the new form of matter to serve as a superconductor, superfluid, or an insulating electronic crystal. In this regard, it could be used to bolster existing technologies, aid the development of new ones, or help to bring clarity to some of the most vexing mysteries of quantum mechanics.
Excitonium is composed of excitons, a combination of electrons and the empty “holes” left by empty electron states. When in an excited state, electrons on the edge of an energy level in an atom can jump to a different energy level, leaving a “hole” behind. This hole then acts with a positive force, trying to pull the negatively charged electron back to its original space. While scientists had envisioned such a state of matter, they were only recently able to identify it through a novel technique. Their work was documented in a study published in the journal Science.
Although further study is needed, the implications of excitonium’s demonstrated existence is substantial. “This result is of cosmic significance,” said study co-author and University of Illinois Professor Peter Abbamonte in a press release. “Ever since the term ‘excitonium’ was coined in the 1960s by Harvard theoretical physicist Bert Halperin, physicists have sought to demonstrate its existence… Since the 1970s, many experimentalists have published evidence of the existence of excitonium, but their findings weren’t definitive proof and could equally have been explained by a conventional structural phase transition.”