A dropleton or quantum droplet is a
quasiparticle
In physics, quasiparticles and collective excitations are closely related emergent phenomena arising when a microscopically complicated system such as a solid behaves as if it contained different weakly interacting particles in vacuum.
For exa ...
comprising a collection of
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
s and
holes
A hole is an opening in or through a particular medium, usually a solid body. Holes occur through natural and artificial processes, and may be useful for various purposes, or may represent a problem needing to be addressed in many fields of en ...
inside a
semiconductor
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...
. Dropletons give the first known quasiparticle characterization where the quasiparticle behaves like a liquid.
The creation of dropletons was announced on 26 February 2014 in a ''
Nature
Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...
'' article, which presented evidence for the creation of dropletons in an
electron–hole plasma inside a
gallium arsenide quantum well
A quantum well is a potential well with only discrete energy values.
The classic model used to demonstrate a quantum well is to confine particles, which were initially free to move in three dimensions, to two dimensions, by forcing them to occupy ...
by ultrashort
laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The fi ...
pulses.
Their existence was not predicted before the experiment.
Despite the relatively short lifetime of about 25
picoseconds, the dropletons are stable enough to be studied
and possess favorable properties for certain investigations of
quantum mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistr ...
. They are approximately 200
nanometers wide, the size of the smallest
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
, for which reason the discoverers have expressed hope that they might one day actually see quantum droplets.
References
{{Particles
Quasiparticles
2014 in science