Quantum
hideIn physics, a quantum (plural: quanta) is an indivisible entity of a quantity that has the same units as the Planck constant and is related to both energy and momentum of elementary particles of matter (called fermions) and of photons and other bosons. The word comes from the Latin "quantus", for "how much." Behind this, one finds the fundamental notion that a physical property may be "quantized", referred to as "quantization". This means that the magnitude can take on only certain discrete numerical values, rather than any value, at least within a range. There is a related term of quantum number.
A photon is often referred to as a "light quantum". The energy of an electron bound to an atom (at rest) is said to be quantized, which results in the stability of atoms, and of matter in general. But these terms can be a little misleading, because what is quantized is this Planck's constant quantity whose units can be viewed as either energy multiplied by time or momentum multiplied by distance.
Usually referred to as quantum "mechanics", it is regarded by virtually every professional physicist as the most fundamental framework we have for understanding and describing nature at the infinitesimal level, for the very practical reason that it works. It is "in the nature of things", not a more or less arbitrary human preference.
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News tagged with quantum
Physicists propose quantum entanglement for motion of microscopic objects
Dec 21, 2009 |
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Researchers at the California Institute of Technology (Caltech) have proposed a new paradigm that should allow scientists to observe quantum behavior in small mechanical systems.
Digital Quantum Battery Could Boost Energy Density Tenfold
Dec 22, 2009 |
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(PhysOrg.com) -- Physicists theorize that quantum phenomena could provide a major boost to batteries, with the potential to increase energy density up to 10 times that of lithium ion batteries. According to ...
Proposed Spacetime Structure Could Provide Hints for Quantum Gravity Theory
Dec 16, 2009 |
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(PhysOrg.com) -- Spacetime, which consists of three dimensions of space and one time dimension, is such a large, abstract concept that scientists have a very difficult time understanding and defining it. Moreover, ...
Google Collaborates with D-Wave on Possible Quantum Image Search
Dec 15, 2009 |
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(PhysOrg.com) -- Always on the cutting edge of new computing technologies, Google has recently announced that it is investigating the use of quantum computing schemes to achieve faster image recognition rates. ...
Does weak equivalence break down at the quantum level?
Dec 08, 2009 |
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(PhysOrg.com) -- One of the givens in physics is the weak equivalence principle. This principle has been considered solid since Einstein proposed that it is not possible to detect the difference between uniform acceleration ...
Hot Electrons Could Double Solar Cell Power Efficiency
Dec 18, 2009 |
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Scientists have experimentally verified a theory suggesting that hot electrons could double the output of solar cells. The researchers, from Boston College, have built solar cells that successfully use hot ...
Researchers Design Triple Quantum Dot for Quantum Information Applications
Nov 30, 2009 |
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(PhysOrg.com) -- While quantum dots have existed since the 1980s, only in the past decade have physicists successfully created lateral few-electron single quantum dots. These quantum dots enable physicists ...
Scientists build 'single-atom transistor'
Dec 06, 2009 |
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(PhysOrg.com) -- Researchers from Helsinki University of Technology (Finland), University of New South Wales (Australia), and University of Melbourne (Australia) have succeeded in building a working transistor, ...
Physicists lay the groundwork for cooler, faster computing
Dec 14, 2009 |
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University of Toronto quantum optics researchers Sajeev John and Xun Ma have discovered new behaviours of light within photonic crystals that could lead to faster optical information processing and compact computers that ...
Using superconducting probes to get a picture of what it's like inside CNTs
Nov 20, 2009 |
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(PhysOrg.com) -- "Carbon nanotubes are exciting for fundamental physics, and for potential technological applications," Nadya Mason tells PhysOrg.com. "However, we are generally limited in the way that we can study them. ...
Building a more versatile laser
Nov 16, 2009 |
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(PhysOrg.com) -- One of the drawbacks associated with using semiconductor lasers is that many of them can only produce a beam of a single wavelength, and can only send that beam in one direction at a time. ...
Fine-tuned: A wholly new approach to tuning a laser's frequency
Dec 04, 2009 |
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(PhysOrg.com) -- For more than 30 years, scientists have been trying to harness the power of terahertz radiation. Tucked between microwaves and infrared rays on the electromagnetic spectrum, terahertz rays ...
Researchers create 'synthetic magnetic fields' for neutral atoms
Dec 02, 2009 |
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(PhysOrg.com) -- Achieving an important new capability in ultracold atomic gases, researchers at the Joint Quantum Institute, a collaboration of the National Institute of Standards and Technology and the University ...
Researchers demonstrate 100-watt-level mid-infrared lasers
Dec 01, 2009 |
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Northwestern University researchers have achieved a breakthrough in quantum cascade laser output power, delivering 120 watts from a single device at room temperature.
Physicist Proposes Solution to Arrow-of-Time Paradox
Aug 27, 2009 |
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(PhysOrg.com) -- Entropy can decrease, according to a new proposal - but the process would destroy any evidence of its existence, and erase any memory an observer might have of it. It sounds like the plot ...
