physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

, polaritons are

boson In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0, 1, 2, ...). Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have half odd-intege ...

quasiparticle In condensed matter physics, a quasiparticle is a concept used to describe a collective behavior of a group of particles that can be treated as if they were a single particle. Formally, quasiparticles and collective excitations are closely relate ...

s resulting from strong coupling of

electromagnetic wave In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength, ...

s (photon) with an electric or magnetic

dipole In physics, a dipole () is an electromagnetic phenomenon which occurs in two ways: * An electric dipole moment, electric dipole deals with the separation of the positive and negative electric charges found in any electromagnetic system. A simple ...

-carrying excitation (state) of solid or liquid matter (such as a

phonon A phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, specifically in solids and some liquids. In the context of optically trapped objects, the quantized vibration mode can be defined a ...

plasmon In physics, a plasmon is a quantum of plasma oscillation. Just as light (an optical oscillation) consists of photons, the plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises from the quant ...

, or an

exciton An exciton is a bound state of an electron and an electron hole which are attracted to each other by the electrostatic Coulomb's law, Coulomb force resulting from their opposite charges. It is an electrically neutral quasiparticle regarded as ...

). Polaritons describe the crossing of the dispersion of light with any interacting

resonance Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...

. They are an expression of level repulsion (

quantum In physics, a quantum (: quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a property can be "quantized" is referred to as "the hypothesis of quantization". This me ...

phenomenon), also known as the avoided crossing principle. To this extent polaritons can be thought of as the new

normal modes A normal mode of a dynamical system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The free motion described by the normal modes takes place at fixed frequencies. ...

of a given material or structure arising from the strong coupling of the bare modes, which are the photon and the dipolar oscillation.

Boson In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0, 1, 2, ...). Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have half odd-intege ...

ic quasiparticles are distinct from polarons (

fermion In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-integer spin (spin 1/2, spin , Spin (physics)#Higher spins, spin , etc.) and obey the Pauli exclusion principle. These particles i ...

ic quasiparticle), which is an electron plus an attached

cloud. Polaritons violate the weak coupling limit and the associated photons do not propagate freely in crystals. Instead, propagation speed depends strongly on the

frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

of the photon. Significant experimental results on various aspects of exciton-polaritons have been gained in the case of

copper(I) oxide Copper(I) oxide or cuprous oxide is the inorganic compound with the formula . It is one of the principal oxides of copper, the other being copper(II) oxide or cupric oxide (CuO). The compound can appear either yellow or red, depending on the size ...

History

Oscillations in ionized gases were observed by

Lewi Tonks Lewi Tonks (1897–July 30, 1971) was an American physicist who worked for General Electric on microwaves, plasma physics and nuclear reactors. Under Irving Langmuir, his work pioneered the study of plasma oscillations. He is also noted for the n ...

and

Irving Langmuir Irving Langmuir (; January 31, 1881 – August 16, 1957) was an American chemist, physicist, and metallurgical engineer. He was awarded the Nobel Prize in Chemistry in 1932 for his work in surface chemistry. Langmuir's most famous publicatio ...

in 1929. Polaritons were first considered theoretically by Kirill Borisovich Tolpygo.K.B. Tolpygo, "Physical properties of a rock salt lattice made up of deformable ions", ''Zh. Eks.Teor. Fiz''. vol. 20, No. 6, pp. 497–509 (1950), English translation: ''Ukrainian Journal of Physics'', vol. 53, special issue (2008); They were termed light-excitons in Soviet scientific literature. That name was suggested by Solomon Isaakovich Pekar, but the term ''polariton,'' proposed by

John Hopfield John Joseph Hopfield (born July 15, 1933) is an American physicist and emeritus professor of Princeton University, most widely known for his study of associative neural networks in 1982. He is known for the development of the Hopfield network. ...

, was adopted. Coupled states of electromagnetic waves and phonons in ionic crystals and their dispersion relation, now known as phonon polaritons, were obtained by Kirill Tolpygo in 1950 and independently by Huang Kun in 1951. Collective interactions were published by David Pines and

David Bohm David Joseph Bohm (; 20 December 1917 – 27 October 1992) was an American scientist who has been described as one of the most significant Theoretical physics, theoretical physicists of the 20th centuryDavid Peat Who's Afraid of Schrödinger' ...

in 1952, and

s were described in silver by Herbert Fröhlich and H. Pelzer in 1955. R.H Ritchie predicted surface plasmons in 1957, then Ritchie and H.B. Eldridge published experiments and predictions of emitted photons from irradiated metal foils in 1962. Otto first published on surface plasmon-polaritons in 1968. Room-temperature superfluidity of polaritons was observed in 2016 by Giovanni Lerario et al., at CNR NANOTEC Institute of Nanotechnology, using an organic microcavity supporting stable Frenkel exciton-polaritons at room temperature. In 2018, scientists reported the discovery of a new three-photon form of

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

, which may involve polaritons and could be useful in

quantum computer A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of both particles and waves, and quantum computing takes advantage of this behavior using specialized hardware. ...

s. In 2024 researchers reported ultrastrong coupling of the PEPI layer in a Fabry-Pérot microcavity consisting of two partially reflective mirrors. The PEPI layer is a two-dimensional

perovskite Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure as , known as the perovskite (stru ...

made of (PEA)2PbI4 (phenethylammonium lead iodide). Placing a PEPI layer within a Fabry-Pérot microcavity forms polaritons and allows control of exciton-exciton annihilation, increasing solar cell efficiency and ED intensity.

Types

A polariton is the result of the combination of a

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that can ...

with a polar excitation in a material. The following are types of polaritons: * Phonon polaritons result from coupling of an

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

photon with an optical

* Exciton polaritons result from coupling of

visible light Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm ...

with an

* Intersubband polaritons result from coupling of an

or terahertz photon with an intersubband excitation * Surface plasmon polaritons result from coupling of surface plasmons with light (the wavelength depends on the substance and its geometry) * Bragg polaritons ("Braggoritons") result from coupling of Bragg photon modes with bulk

s * Plexcitons result from coupling

s with excitons * Magnon polaritons result from coupling of magnon with light * Pi-tons result from coupling of alternating charge or spin fluctuations with light, distinctly different from magnon or exciton polaritons * Cavity polaritons

References

External links

YouTube animation explaining what is polariton in a semiconductor micro-resonator.

Description of the experimental research on polariton fluids at the Institute of Nanotechnologies.
{{Authority control Quasiparticles

History

Types

See also

References

Further reading

External links