It's a solid, it's a liquid, it's a dropleton

Scientists said Wednesday they had discovered a new type of microscopic particle cluster that is found in solid materials but strangely behaves like a liquid. They called it the "dropleton". The new entity, infinitely small and with a blink-and-you-miss-it lifespan, is a quasiparticle -- a combination of other, fundamental particles with unusual properties that exist in solids. "The dropleton is a new element -- a stable building block to build more complicated many-particle constructions in solids," study co-author Mackillo Kira of the Philipps-University Marburg in Germany told AFP of the discovery. "Our discovery adds a new element to the 'periodic table' of existing quasiparticles in solids." Each dropleton or "quantum droplet" is thought to comprise about five electrons and five quantum "holes" -- spaces in solid matter where an electron once was, according to a paper published in the journal Nature. Stimulated by light, this combination of smaller particles briefly condense into a "droplet" with characteristics of liquid water, which includes that it can have ripples. The dropleton exists for a mere 25 picoseconds (trillionths of a second). Though fleeting, this is long enough for researchers to study how light interacts with specialised forms of matter, according to a statement from the US National Institute of Standards and Technology (NIST), which took part in the study. The dropleton was discovered when researchers bombarded a  semiconductor made of gallium arsenide with lasers at a rate of 100 million pulses per second in search of new quasiparticles. The main use of the discovery is to understand more about how photons, or particles of light, can react with matter. But the dropleton's high sensitivity to light could also give it an application in light-detecting electronic devices. Another example of a quasiparticle is the exciton, which is comprised of one electron and one "hole", attracted to one another by electrostatic forces.