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
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 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 ...
Wizard at circuits, physics
Dec 03, 2009 |
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(PhysOrg.com) -- Donhee Ham, Gordon McKay Professor of Electrical Engineering and Applied Physics, uses his personal energy and understanding of physics to design innovative integrated circuits.
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.
First Pump-Probe Experiment at Linac Coherent Light Source Completed
Nov 30, 2009 |
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(PhysOrg.com) -- The first experiment using the Linac Coherent Light Source to illuminate molecules via a "pump-probe" technique has been completed by an international team of more than 30 scientists from ...
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. ...
Physicist Jack Harris Is Honored by DARPA as One of Nation's 'Rising Stars'
Dec 04, 2009 |
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(PhysOrg.com) -- Jack Harris, an associate professor of physics, has received one of this year's Young Faculty Awards (YFA) from the Defense Advanced Research Projects Agency (DARPA). He is one of 33 "rising stars" across ...
UCSB physicists move one step closer to quantum computing
Nov 20, 2009 |
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Physicists at UC Santa Barbara have made an important advance in electrically controlling quantum states of electrons, a step that could help in the development of quantum computing. The work is published ...
New study confirms exotic electric properties of graphene
Nanotechnology / Nanomaterials
Nov 17, 2009 |
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(PhysOrg.com) -- First, it was the soccer-ball-shaped molecules dubbed buckyballs. Then it was the cylindrically shaped nanotubes. Now, the hottest new material in physics and nanotechnology is graphene: ...
Scientists demonstrate 'universal' programmable quantum processor
Nov 15, 2009 |
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Physicists at the National Institute of Standards and Technology have demonstrated the first "universal" programmable quantum information processor able to run any program allowed by quantum mechanics -- th ...
A line on string theory
Nov 12, 2009 |
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(PhysOrg.com) -- A Harvard theoretical physicist has discussed with scientists at the Large Hadron Collider in Switzerland the possibility that they may discover a theorized "stau" particle, with a lifetime ...
Straightening messy correlations with a quantum comb
Nov 23, 2009 |
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Quantum computing promises ultra-fast communication, computation and more powerful ways to encrypt sensitive information. But trying to use quantum states as carriers of information is an extremely delicate ...
Visual assistance for cosmic blind spots
Nov 23, 2009 |
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A bit of imagination on the part of a measuring instrument wouldn't be a bad thing. It could help to add data from areas where the instrument is unable to measure. However, it must do so constructively. In ...
