By Andrew Grant
A never-before-seen microscopic droplet has emerged amid a flood of laser light. This quantum droplet is the latest addition to a growing population of quasiparticles: collections of subatomic particles that behave like single entities.
One way to create a quasiparticle is to fire a laser at gallium arsenide, a semiconductor used in solar panels, DVD players and light-emitting diodes (SN: 6/29/13, p. 16). The laser injects energy, causing the material’s resident electrons to jump to a higher energy state. The negatively charged electrons leave behind positively charged holes. Individual pairs of electrons and holes attract one another, creating quasiparticles called excitons.