Polariton

Dispersion relation of polaritons in GaP. Red curves are the uncoupled phonon and photon dispersion relations, black curves are the result of coupling (from top to bottom: upper polariton, LO phonon, lower polariton).

In physics, polaritons /pɵˈlærɪtɒnz/ are quasiparticles resulting from strong coupling of electromagnetic waves with an electric or magnetic dipole-carrying excitation. They are an expression of the common quantum phenomenon known as level repulsion, also known as the avoided crossing principle. Polaritons describe the crossing of the dispersion of light with any interacting resonance.

Types of Polaritons

Thus, a polariton is the result of the mixing of a photon with an excitation of a material. The following are types of polaritons:

• Phonon-polaritons result from coupling of an infrared photon with an optic phonon;
• Exciton-polaritons result from coupling of visible light with an exciton
• intersubband-polaritons result from coupling of an infrared or terahertz photon with an intersubband excitation.
• Surface plasmon polaritons, resulting from coupling of surface plasmons with light (the wavelength depends on the substance and its geometry).
• Bragg-polaritons or Braggoritons, have been observed^[1] and studied theoretically.

Principles of Polaritons

Whenever the polariton picture is valid, the model of photons propagating freely in crystals is insufficient. A major feature of polaritons is a strong dependency of the propagation speed of light through the crystal on the frequency. For exciton-polaritons, rich experimental results on various aspects have been gained in copper (I) oxide.

The polariton is a bosonic quasiparticle, and should not be confused with the polaron, a fermionic one, e.g. an electron plus attached phonon cloud. Polaritons were first considered theoretically by Kirill Borisovich Tolpygo,^[2][3] a Ukrainian physicist, and were initially termed light-excitons in Ukrainian and Russian scientific literature.

See also

• Atomic coherence
• Polariton laser
• Polariton superfluid
• Polaritonics

References

• Fano, U. (1956). "Atomic Theory of Electromagnetic Interactions in Dense Materials". Physical Review 103 (5): 1202–1218. Bibcode:1956PhRv..103.1202F. doi:10.1103/PhysRev.103.1202. 
• Hopfield, J. J. (1958). "Theory of the Contribution of Excitons to the Complex Dielectric Constant of Crystals". Physical Review 112 (5): 1555–1567. Bibcode:1958PhRv..112.1555H. doi:10.1103/PhysRev.112.1555. 

Further reading

• Baker-Jarvis, J. (2012). "The Interaction of Radio-Frequency Fields With Dielectric Materials at Macroscopic to Mesoscopic Scales". Journal of Research of the National Institute of Standards and Technology (National Institute of Science and Technology) 117: 1. doi:10.6028/jres.117.001. 

v t e Particles in physics Elementary Fermions Quarks u u d d c c s s t t b b Leptons e− e+ μ− μ+ τ− τ+ ν e ν e ν μ ν μ ν τ ν τ Bosons Gauge γ g W± · Z Scalar H0 Others Ghosts Hypothetical Superpartners Gauginos Gluino Gravitino Others Axino Chargino Higgsino Neutralino Sfermion Others A0 Dilaton G J Majorana fermion m Tachyon X Y W' Z' Sterile neutrino Composite Hadrons Baryons / Hyperons N p n Δ Λ Σ Ξ Ω Mesons / Quarkonia π ρ η η′ φ ω J/ψ ϒ θ K B D T Others Atomic nuclei Atoms Diquarks Exotic atoms Positronium Muonium Tauonium Onia Superatoms Molecules Hypothetical Exotic hadrons Exotic baryons Dibaryon Pentaquark Skyrmion Exotic mesons Glueball Tetraquark Others Mesonic molecule Pomeron Quasiparticles Davydov soliton Exciton Hole Magnon Phonon Plasmaron Plasmon Polariton Polaron Roton Trion Lists Baryons Mesons Particles Quasiparticles Timeline of particle discoveries Wikipedia books Hadronic Matter Particles of the Standard Model Leptons Quarks Physics portal