photon

A quantum of electromagnetic radiation — the elementary particle of light, having zero rest mass and travelling at the speed of light. It exhibits both wave and particle properties.

• photonic/foʊˈtɒnɪk/(adj)光子的
• photonics(n)光子学

• photon energy
• photon emission
• single photon
• photon absorption
• photon detector

1. 1.Every photon carries a specific amount of energy determined by its frequency — blue photons carry more energy than red ones, which is why ultraviolet light can cause sunburn. (light particle)
2. 2.Quantum encryption relies on a fundamental property of photons: measuring a photon's state inevitably changes it, making eavesdropping detectable. (quantum property)

• light quantum (the original term)
• light particle (informal)

from Greek "phos" (light) + "-on" (particle suffix, as in electron, proton) — coined by Gilbert Lewis in 1926 — the particle of light