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
Scientists create first electronic quantum processor
Jun 28, 2009 |
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A team led by Yale University researchers has created the first rudimentary solid-state quantum processor, taking another step toward the ultimate dream of building a quantum computer.
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 ...
A broadband single-photon source
Sep 19, 2008 |
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As science makes progress toward practical quantum computing, improved quantum cryptography and scalable quantum communications systems, single photon sources will become more important. Until now, though, ...
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 ...
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 ...
A sonic boom in the world of lasers
Jun 17, 2009 |
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It was an idea born out of curiosity in the physics lab, but now a new type of ‘laser’ for generating ultra-high frequency sound waves instead of light has taken a major step towards becoming a unique and highly useful 21st ...
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Shaking the Fundamentals of Physics: At the Limits of the Photoelectric Effect
Apr 24, 2009 |
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With extremely short wavelengths and very high intensities, light-matter interaction seems to be different than previously accepted.
'Colossal' Magnetic Effect Under Pressure
Jun 05, 2009 |
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(PhysOrg.com) -- Millions of people today carry around pocket-sized music players capable of holding thousands of songs, thanks to the discovery 20 years ago of a phenomenon known as the “giant magnetoresistance ...
Turning sunlight into liquid fuels (Video)
Mar 11, 2009 |
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(PhysOrg.com) -- For millions of years, green plants have employed photosynthesis to capture energy from sunlight and convert it into electrochemical energy. A goal of scientists has been to develop an artificial ...
New method to detect quantum mechanical effects in ordinary objects
Jun 22, 2009 |
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At the quantum level, the atoms that make up matter and the photons that make up light behave in a number of seemingly bizarre ways. Particles can exist in "superposition," in more than one state at the same ...
Atom Pinhole Camera Acts as a Shrinking Copy Machine
Jun 01, 2009 |
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(PhysOrg.com) -- In 1983, Richard Feynman proposed the idea of a machine that could create smaller scale replicas of itself. Today, such a system is still a challenge, but a machine that can produce nanometer-sized ...
Manipulating light on a chip for quantum technologies
Jun 05, 2009 |
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(PhysOrg.com) -- A team of physicists and engineers at Bristol University has demonstrated exquisite control of single particles of light — photons — on a silicon chip to make a major advance towards long-sought-after ...
Ghost remains after black hole eruption
May 28, 2009 |
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NASA's Chandra X-ray Observatory has found a cosmic "ghost" lurking around a distant supermassive black hole. This is the first detection of such a high-energy apparition, and scientists think it is evidence ...
Researchers make breakthrough in the quantum control of light
May 29, 2009 |
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Researchers at UC Santa Barbara have recently demonstrated a breakthrough in the quantum control of photons, the energy quanta of light. This is a significant result in quantum computation, and could eventually ...
Planetary Society plans new 'solar sail'
Space & Earth / Space Exploration
Nov 09, 2009 |
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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 ...
