Quasiparticle

The term Quasiparticle describes a concept in physics in which energetically excited states in matter are treated as though they are elementary quantum particles in their own right.  In fact they may be something less tangible like a vibration or a rotation.

Unlike neutrons, protons, or even atoms and molecules, quasiparticles aren't independent structures floating about on their own in free space but exist only within the structure being studied.

For the purposes of modelling the behaviour of the excited state within the structure this treatment works very well.  

As the particles emerge from more fundamental structures they are called quasi-particles or quasiparticles.

These particles have in most cases short  lifetimes, like the magnon or the exciton. But there are also some quasi-particles with an infinite lifetime like the cooper-pair in superconductors.

List of known quasiparticles

Quasiparticles

Quasiparticle	Signification	Underlying particles
Anyon	A type of quasiparticle that occurs only in two-dimensional systems, with properties much less restricted than fermions and bosons.
Bion	A bound state of solitons, named for Born-Infeld model	soliton
Bipolaron	A bound pair of two polarons	polaron (electron, phonon)
Bogoliubon	Broken Cooper pair	electron, hole
Configuron	An elementary configurational excitation in an amorphous material which involves breaking of a chemical bond
Cooper pair	A pair of free electrons within a solid that act together as one quasiparticle and gives rise to superconductivity.	electron
Dislon	Associated with a dislocation in lattice structure in crystalline solids. It emerges from the quantization of the lattice displacement field of a classical dislocation
Dropleton	The first known quasiparticle that behaves like a liquid
Electron quasiparticle	An electron as affected by the other forces and interactions in the solid	electron
Electron hole (hole)	A lack of electron in a valence band	electron, cation
Exciton	A bound state of an electron and a hole	electron, hole
Fracton	A collective quantized vibration on a substrate with a fractal structure.
Fracton (subdimensional particle)	An emergent quasiparticle excitation that is immobile when in isolation.
Holon (chargon)	A quasi-particle resulting from electron spin-charge separation
Leviton	A collective excitation of a single electron within a metal
Magnon	A coherent excitation of electron spins in a material
Majorana fermion	A quasiparticle equal to its own antiparticle, emerging as a midgap state in certain superconductors
Nematicon	A soliton in nematic liquid crystal media
Orbiton	A quasiparticle resulting from electron spin-orbital separation
Oscillon	A soliton-like single wave in vibrating media
Phason	Vibrational modes in a quasicrystal associated with atomic rearrangements
Phoniton	A theoretical quasiparticle which is a hybridization of a localized, long-living phonon and a matter excitation
Phonon	Vibrational modes in a crystal lattice associated with atomic shifts
Plasmaron	A quasiparticle emerging from the coupling between a plasmon and a hole
Plasmon	A coherent excitation of a plasma
Polaron	A moving charged quasiparticle that is surrounded by ions in a material	electron, phonon
Polariton	A mixture of photon with other quasiparticles	photon, optical phonon
Roton	Elementary excitation in superfluid helium-4
Soliton	A self-reinforcing solitary excitation wave
Spinon	A quasiparticle produced as a result of electron spin-charge separation that can form both quantum spin liquid and strongly correlated quantum spin liquid
Trion	A coherent excitation of three quasiparticles (two holes and one electron or two electrons and one hole)
Wrinklon	A localized excitation corresponding to wrinkles in a constrained two dimensional system

Quasiparticle Media

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  Any system, no matter how complicated, has a ground state along with an infinite series of higher-energy excited states.