What is photon?

  • (noun): A quantum of electromagnetic radiation; an elementary particle that is its own antiparticle.


A photon is an elementary particle, the quantum of light and all other forms of electromagnetic radiation, and the force carrier for the electromagnetic force, even when static via virtual photons. The effects of this force are easily observable at both the microscopic and macroscopic level, because the photon has no rest mass; this allows for interactions at long distances. Like all elementary particles, photons are currently best explained by quantum mechanics and exhibit wave–particle duality, exhibiting properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference with itself, but also act as a particle giving a definite result when its position is measured.

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Some articles on photon:

Manipulation Of Atoms By Optical Field
... A cold atom absorbs a photon from one of the laser beams and emits in the other beam receiving a net momentum of in the direction of the photon ... This is called two-photon recoil process ... The clouds then travel in opposite directions with a velocity, in the direction of the photon ...
Photon - Recent Research
... research has been devoted to applications of photons in the field of quantum optics ... Photons seem well-suited to be elements of an extremely fast quantum computer, and the quantum entanglement of photons is a focus of research ... Nonlinear optical processes are another active research area, with topics such as two-photon absorption, self-phase modulation, modulational instability and optical parametric oscillators ...
Superconducting Camera
... The superconducting camera, SCAM, is an ultra-fast photon-counting camera developed by the European Space Agency ... junction detectors, to register almost every photon of light that falls into it ... can measure both the brightness (rate) of the incoming photon stream and the colour (wavelength or energy) of each individual photon ...