Tiny light box opens new doors into the nanoworld

Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nano level. Using a tiny box, built from stacked atomically thin material, ...

A new candidate for dark matter and a way to detect it

Two theoretical physicists at the University of California, Davis have a new candidate for dark matter, and a possible way to detect it. They presented their work June 6 at the Planck 2019 conference in Granada, Spain and ...

Chemists build a better cancer-killing drill

An international team of scientists is getting closer to perfecting molecule-sized motors that drill through the surface of cancer cells, killing them in an instant.

Quantum information gets a boost from thin-film breakthrough

Efforts to create reliable light-based quantum computing, quantum key distribution for cybersecurity, and other technologies got a boost from a new study demonstrating an innovative method for creating thin films to control ...

Experts develop nanolasers on silicon

Researchers at Cardiff University have shown tiny light-emitting nanolasers less than a tenth of the size of the width of a human hair can be integrated into silicon chip design.

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Photon

In physics, a photon is an elementary particle, the quantum of the electromagnetic field and the basic "unit" of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force. 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 governed by quantum mechanics and will exhibit wave-particle duality – they exhibit properties of both waves and particles. For example, a single photon may be refracted by a lens or exhibit wave interference, but also act as a particle giving a definite result when its location is measured.

The modern concept of the photon was developed gradually by Albert Einstein to explain experimental observations that did not fit the classical wave model of light. In particular, the photon model accounted for the frequency dependence of light's energy, and explained the ability of matter and radiation to be in thermal equilibrium. It also accounted for anomalous observations, including the properties of black body radiation, that other physicists, most notably Max Planck, had sought to explain using semiclassical models, in which light is still described by Maxwell's equations, but the material objects that emit and absorb light are quantized. Although these semiclassical models contributed to the development of quantum mechanics, further experiments proved Einstein's hypothesis that light itself is quantized; the quanta of light are photons.

In the modern Standard Model of particle physics, photons are described as a necessary consequence of physical laws having a certain symmetry at every point in spacetime. The intrinsic properties of photons, such as charge, mass and spin, are determined by the properties of this gauge symmetry.

The photon concept has led to momentous advances in experimental and theoretical physics, such as lasers, Bose–Einstein condensation, quantum field theory, and the probabilistic interpretation of quantum mechanics. It has been applied to photochemistry, high-resolution microscopy, and measurements of molecular distances. Recently, photons have been studied as elements of quantum computers and for sophisticated applications in optical communication such as quantum cryptography.

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