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

|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||