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 photons
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 ...
Quantum technologies move a step closer with the demonstration of an 'entanglement' filter
Jan 22, 2009 |
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(PhysOrg.com) -- A team of physicists and engineers has demonstrated an optical device that filters two particles of light (or photons) based on the correlations between their polarisation that are only allowed in the seemingly ...
Using 'slow light' to modulate single photon wavepackets
Sep 11, 2008 |
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(PhysOrg.com) -- Single photons have been studied for a long time, Steve Harris tells PhysOrg.com. “But this is the first time that their wavepackets have been modulated.” Just as electrons may be described as either particles ...
Austrian breakthrough in quantum cryptography: Record in the transmission of entangled photon pairs (Update)
May 03, 2009 |
3.7 / 5 (11) |
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Austrian physicists say a breakthrough in next-generation quantum cryptography could allow encrypted messages to be bounced off satellites, the British journal Nature reported Sunday.
EVE: Measuring the Sun's hidden variability
Space & Earth / Space Exploration
Sep 22, 2009 |
4.1 / 5 (7) |
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Every 11 years, the sun undergoes a furious upheaval. Dark sunspots burst forth from beneath the sun's surface. Explosions as powerful as a billion atomic bombs spark intense flares of high-energy radiation. ...
High-speed signal mixer demonstrates capabilities of transistor laser
Mar 19, 2009 |
5 / 5 (1) |
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(PhysOrg.com) -- Scientists at the University of Illinois have successfully demonstrated a microwave signal mixer made from a tunnel-junction transistor laser. Development of the device brings researchers ...
Physicists Seek Answers to Quantum Correlations
Aug 14, 2008 |
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After performing multiple tests on two entangled photons, physicists have yet again found that the photons seem to be communicating faster than the speed of light - at least 100,000 times faster. The researchers ...
Quantum calibration paves way for super-secure communication
Nov 17, 2008 |
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(PhysOrg.com) -- A new approach to calibrating quantum mechanical measurement has been developed with particular applications in optics and super-secure quantum communication.
Light sensor breakthrough could enhance digital cameras
Jun 18, 2009 |
3.8 / 5 (4) |
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New research by a team of University of Toronto scientists could lead to substantial advancements in the performance of a variety of electronic devices including digital cameras.
Siemens builds a lock made of light: Data transfer using quantum cryptography
Aug 01, 2008 |
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(PhysOrg.com) -- Electronic communication is becoming more secure all over the world. Siemens IT Solutions and Services, Austrian Research Centers (ARC) and Graz University of Technology have joined forces ...
