Photon
hideIn 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.
For more information about Photon, read the full article at
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News tagged with photon
JQI researchers create entangled photons from quantum dots
Nov 18, 2009 |
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To exploit the quantum world to the fullest, a key commodity is entanglement—the spooky, distance-defying link that can form between objects such as atoms even when they are completely shielded from one another. Now, physicists ...
Argonne 'homegrown' hybrid solar cell aims for low-cost power
Nanotechnology / Nanomaterials
Nov 10, 2009 |
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(PhysOrg.com) -- Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have refined a technique to manufacture solar cells by creating tubes of semiconducting material and then "growing" ...
Planetary Society plans new 'solar sail'
Space & Earth / Space Exploration
Nov 09, 2009 |
4.7 / 5 (14) |
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(AP) -- Four years after its first solar sail ended up in the ocean instead of orbit, The Planetary Society announced Monday that by the end of 2010 it will try again to launch a spacecraft that will be propelled by the ...
Highlight: STM banopatterning on pristine Nb-doped SrTiO3 surfaces
Nov 04, 2009 |
5 / 5 (2) |
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Collaborative users from the Advanced Photon Source at the Argonne National Laboratory, working with the Electronic & Magnetic Materials & Devices Group, have found a controllable way to modify the surfaces ...
Creating a six-qubit cluster state
Nov 02, 2009 |
4.6 / 5 (10) |
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(PhysOrg.com) -- Many scientists believe that quantum entanglement is required in order for effective quantum computing. Entanglement takes place when there is a connection that exists between two objects - even when they ...
Gamma-ray photon race ends in dead heat; Einstein wins this round
Oct 28, 2009 |
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Racing across the universe for the last 7.3 billion years, two gamma-ray photons arrived at NASA's orbiting Fermi Gamma-ray Space Telescope within nine-tenths of a second of one another. The dead-heat finish ...
Fermi Telescope Caps First Year With Glimpse of Space-Time (w/ Video)
Oct 28, 2009 |
4.6 / 5 (14) |
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During its first year of operations, NASA's Fermi Gamma Ray Space Telescope mapped the extreme sky with unprecedented resolution and sensitivity. It captured more than one thousand discrete sources of gamma ...
3D CMOS camera for your mobile?
Oct 14, 2009 |
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(PhysOrg.com) -- European researchers have created a world-leading camera in CMOS that can record photons at a million times a second. Best of all, it will be really cheap to manufacture, offering applications ...
Researchers fine-tune diffuse optical tomography for breast cancer screening
Oct 06, 2009 |
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Clemson University researchers in collaboration with researchers at the University of Bremen, Germany, are working to make the physical pain and discomfort of mammograms a thing of the past, while allowing for diagnostic ...
Building a better qubit: Combining 6 photons together results in highly robust qubits
Oct 05, 2009 |
5 / 5 (2) |
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Exploiting quantum mechanics for transmitting information is a tantalizing possibility because it promises secure, high speed communications. Unfortunately, the fragility of methods for storing and sending ...
Filming photons, one million times a second
Oct 05, 2009 |
4.7 / 5 (9) |
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(PhysOrg.com) -- European researchers have created a CMOS (semiconductor) camera capable of filming individual photons one million times a second. The breakthrough will impact on all the most advanced areas ...
Physicists Explain How Human Eyes Can Detect Quantum Effects
Sep 29, 2009 |
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(PhysOrg.com) -- By greatly amplifying one photon from an entangled photon pair, physicists have theoretically shown that human eyes can be used as detectors to observe quantum effects. Usually, detecting ...
Researchers develop thin films showing promise for solar applications
Nanotechnology / Nanomaterials
Sep 08, 2009 |
4.1 / 5 (8) |
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Researchers at Ben-Gurion University of the Negev have developed thin films that exhibit carrier multiplication (CM). This development is of great interest for future solar cells.
First-ever calculation performed on optical quantum computer chip
Sep 03, 2009 |
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(PhysOrg.com) -- A primitive quantum computer that uses single particles of light (photons) whizzing through a silicon chip has performed its first mathematical calculation. This is the first time a calculation ...
Coherent X-Ray Diffraction Patterns of Collagen Measured in Soft Tissues
Sep 01, 2009 |
3 / 5 (4) |
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Coherent X-ray Diffraction patterns of collagen in soft tissues have been measured for the first time by Dr Felisa Berenguer at the London Centre for Nanotechnology with her colleagues.
