JILA physicists from the National Institute of Standards and Technology (NIST) and University of Colorado Boulder have discovered a new semiconductor quasiparticle called a “quantum droplet” or “dropleton”.
Quasiparticles are groups of smaller particles that act together in a predictable way, and in the dropleton the particles briefly condense into a liquid-like droplet. Pressure from the surrounding plasma only holds the dropleton together for 25 picoseconds, 25 trillionths of a second, but this is long enough for scientists to see how it interacts with light.
The researchers created the quasiparticles by pulsing an ultrafast red laser through a gallium-arsenide semiconductor at 100 million times per second. These pulses form excitons, with more electron-hole pairs created as the intensity increases, and dropletons forming when exciton density reaches a certain level.