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
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 ...
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 ...
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. ...
Creating a six-qubit cluster state
Nov 02, 2009 |
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(PhysOrg.com) -- Many scientists believe that quantum entanglement is required in order for effective quantum computing. Entanglement takes place when there is a connection that exists between two objects - even when they ...
Study Shows Time Traveling May Not Increase Computational Power
Oct 22, 2009 |
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(PhysOrg.com) -- For more than 50 years, physicists have been intrigued by the concept of closed time-like curves (CTCs). Because a CTC returns to its starting point, it raises the possibility of traveling backward in time. ...
Atomtronic transistor and diode could advance quantum computing
Oct 09, 2009 |
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(PhysOrg.com) -- What if atoms could be used to perform the functions currently the province of electronic devices? The goal of atomtronics is to do just that by creating analogues to the common items found in electronic ...
Physicists Demonstrate Three-Color Entanglement
Oct 07, 2009 |
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(PhysOrg.com) -- For the first time, physicists have demonstrated the quantum entanglement of three light beams, all of different wavelengths. Entanglement of two light beams of different wavelengths has already ...
Physicists Investigate Unusual Four-Qubit Entanglement
Sep 30, 2009 |
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(PhysOrg.com) -- For the first time, physicists have experimentally demonstrated a four-qubit bound-entangled state - a peculiar form of entanglement that cannot be distilled (optimized) by the usual means. ...
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 ...
Proposed Quantum Computer Consists of Billions of Electron Spins
Sep 09, 2009 |
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(PhysOrg.com) -- While researchers have already demonstrated the building blocks for few-bit quantum computers, scaling these systems up to large quantum computers remains a challenge. One of the biggest problems ...
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 ...
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 ...
New Law of Physics Could Explain Quantum Mysteries
Aug 17, 2009 |
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(PhysOrg.com) -- Since the early days of quantum mechanics, scientists have been trying to understand the many strange implications of the theory: superpositions, wave-particle duality, and the observer’s ...
Researchers Set New Distance Record for Quantum Key Distribution
Jul 21, 2009 |
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(PhysOrg.com) -- Quantum key distribution (QKD) could be the next commercial success of quantum physics, and a recent study has taken the field a step closer to this reality. Researchers from the University ...
