photon

noun

pho·​ton ˈfō-ˌtän 

1

: a quantum of electromagnetic radiation

Should a substance happen to have a lot of electrons in a higher level, and a lower level is mostly empty …, then a photon can cause an electron to transfer from a higher state to a lower one. This change releases energy and creates a new photon, in addition to the one which caused the transfer. This photon can in turn induce more electrons to fall to a lower state.

—Robert Gilmore

2

dated : troland

photonic

fō-ˈtä-nik 

adjective

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Science and the Photon

It was Albert Einstein who first theorized that the energy in a light beam exists in small bits or particles, and scientists today know that light sometimes behaves like a wave (somewhat like sound or water) and sometimes like a stream of particles. The energies of photons range from high-energy gamma rays and X-rays down to low-energy infrared and radio waves, though all travel at the same speed. The amazing power of lasers is the result of a concentration of photons that have been made to travel together in order to hit their target at the same time.

Examples of photon in a Sentence

Recent Examples on the Web

According to theory, the particles that carry that force — bosons — should be massless, like the photon that transmits light. —Dennis Overbye, New York Times, 9 Apr. 2024

The electromagnetic force is long range because the photon has no mass, and the weak force is short range because the particles that convey it, the W and Z, are massive. —Byadrian Cho, science.org, 28 Mar. 2024

When hit by photons, the dots emit electrons that flow across the graphene sheet to produce a current. —The Physics Arxiv Blog, Discover Magazine, 21 Mar. 2024

The photons pass through a gain medium, a material that creates a cascade of additional photons, which rapidly increases the number of photons. —Iain Boyd, The Conversation, 7 Mar. 2024

The key difference is that this rare event involves two photons instead of one — both incoming and outgoing photons. —Quanta Magazine, 14 Mar. 2024

But doing so also hinders the efficient capture and guidance of emitted photons via the fiber’s internal optic mode, also known as channeling efficiency—the mechanism by which the photons are coupled into and channeled through the fiber based on the fiber’s structure. —IEEE Spectrum, 10 Jan. 2024

In contrast, quantum computers utilize quantum bits, or qubits, which are quantum objects like electrons or photons. —Craig S. Smith, Forbes, 28 Nov. 2023

This let the sensor detect photons of all polarizations, boosting its efficiency. —IEEE Spectrum, 1 Feb. 2024

Word History

Etymology

phot- + -on entry 2

First Known Use

1916, in the meaning defined at sense 2

Kids Definition

photon

noun

pho·​ton ˈfō-ˌtän 

: a tiny particle or bundle of electromagnetic radiation

Medical Definition

photon

noun

pho·​ton ˈfō-ˌtän 

1

: a unit of intensity of light at the retina equal to the illumination received per square millimeter of a pupillary area from a surface having a brightness of one candela per square meter

called also troland

2

: a quantum of electromagnetic radiation