Scientists at the University of Colorado Joint Institute for Lab Astrophysics have discovered a new form of matter called dropletons.
This discovery came when the team was attempting to create excitons. Excitons are formed when a photon hits a semiconductor. Sometimes, an electron escapes, leaving an electron hole and if the electron is nearby and is attracted to the electron hole, an exciton is formed.
Graduate student Andrew Almand-Hunter was attempting to create biexcitons – that’s two excitons that act like a molecule – and was while using a laser to create excitons came across this discovery.
“… The experiment didn’t behave at all in the way we expected,” said Almand-Hunter. “We expected to see the energy of the biexcitons increase as the laser generated more electrons and holes. But, what we saw when we did the experiment was that the energy actually decreased.”
The team wasn’t sure what they made, but after contacting theorists at Phillipps-University, Marburg, a model of the dropletons’ behavior was generated.
“The dropletons are small enough to behave quantum mechanically, but the electrons and holes are not in pairs, as they would be if the dropleton was just a group of excitons. Instead they form a “quantum fog” of electrons and holes that flow around each other and even ripple like a liquid, rather than existing as discrete pairs. However, unlike liquids we are familiar with, dropletons a finite size, outside which the electron/hole association breaks down.”
Dropletons only exist inside solid materials and last around 25 trillionths of a second. However, that is long enough to give scientists the opportunity to study them.