News tagged with quantum
Repulsive gravity as an alternative to dark energy (Part 2: In the quantum vacuum)
(PhysOrg.com) -- During the past few years, CERN physicist Dragan Hajdukovic has been investigating what he thinks may be a widely overlooked part of the cosmos: the quantum vacuum. He suggests that the quantum vacuum has ...
Scientists create light from vacuum
(PhysOrg.com) -- Scientists at Chalmers University of Technology have succeeded in creating light from vacuum observing an effect first predicted over 40 years ago. The results will be published tomorrow ...
Nov 17, 2011 |
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Four reasons why the quantum vacuum may explain dark matter
(PhysOrg.com) -- Earlier this year, PhysOrg reported on a new idea that suggested that gravitational charges in the quantum vacuum could provide an alternative to dark matter. The idea rests on the hypothesis that particles ...
Single-atom transistor is 'perfect'
In a remarkable feat of micro-engineering, UNSW physicists have created a working transistor consisting of a single atom placed precisely in a silicon crystal.
Feb 19, 2012 |
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Seeing quantum mechanics with the naked eye
(PhysOrg.com) -- A Cambridge team have built a semiconductor chip that converts electrons into a quantum state that emits light but is large enough to see by eye. Because their quantum superfluid is simply ...
Jan 09, 2012 |
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Scientists report first solar cell producing more electrons in photocurrent than solar photons entering cell
(PhysOrg.com) -- Researchers from the National Renewable Energy Laboratory (NREL) have reported the first solar cell that produces a photocurrent that has an external quantum efficiency greater than 100 percent when photoexcited ...
Dec 15, 2011 |
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Time reversal: A simple particle could reveal new physics
(PhysOrg.com) -- A simple atomic nucleus could reveal properties associated with the mysterious phenomenon known as time reversal and lead to an explanation for one of the greatest mysteries of physics: the ...
Oct 11, 2011 |
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Why we've got the cosmological constant all wrong
(PhysOrg.com) -- Some scientists call the cosmological constant the "worst prediction of physics." And when todays theories give an estimated value that is about 120 orders of magnitude larger than the ...
Does the quantum wave function represent reality?
(Phys.org) -- At the heart of quantum mechanics lies the wave function, a probability function used by physicists to understand the nanoscale world. Using the wave function, physicists can calculate a system's ...
In the quantum world, diamonds can communicate with each other
Researchers working at the Clarendon Laboratory at the University of Oxford in England have managed to get one small diamond to communicate with another small diamond utilizing "quantum entanglement," one ...
Dec 02, 2011 |
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Physicists propose test for loop quantum gravity
(PhysOrg.com) -- As a quantum theory of gravity, loop quantum gravity could potentially solve one of the biggest problems in physics: reconciling general relativity and quantum mechanics. But like all tentative ...
Quantum levitating (locking) video goes viral
(PhysOrg.com) -- A video created by researchers at Tel Aviv University in Israel has the Internet buzzing. Though rather simple, it just looks really cool, hence all the attention. Its a demonstration of ...
Looking at quantum gravity in a mirror
Einstein's theory of gravity and quantum physics are expected to merge at the Planck-scale of extremely high energies and on very short distances. At this scale, new phenomena could arise. However, the Planck-scale ...
Mar 18, 2012 |
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Quantum computer built inside a diamond
Diamonds are forever or, at least, the effects of this diamond on quantum computing may be. A team that includes scientists from USC has built a quantum computer in a diamond, the first of its kind to include protection ...
Apr 04, 2012 |
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Quantum physics mimics spooky action into the past
Physicists of the group of Prof. Anton Zeilinger at the Institute for Quantum Optics and Quantum Information (IQOQI), the University of Vienna, and the Vienna Center for Quantum Science and Technology (VCQ) ...
Apr 23, 2012 |
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Quantum
In 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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