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2Physics Quote:
"Lasers are light sources with well-defined and well-manageable properties, making them an ideal tool for scientific research. Nevertheless, at some points the inherent (quasi-) monochromaticity of lasers is a drawback. Using a convenient converting phosphor can produce a broad spectrum but also results in a loss of the desired laser properties, in particular the high degree of directionality. To generate true white light while retaining this directionality, one can resort to nonlinear effects like soliton formation."
-- Nils W. Rosemann, Jens P. Eußner, Andreas Beyer, Stephan W. Koch, Kerstin Volz, Stefanie Dehnen, Sangam Chatterjee
(Read Full Article: "Nonlinear Medium for Efficient Steady-State Directional White-Light Generation"
)

Monday, November 20, 2006

Breakthrough in Quantum Computing

Christoph Boehme of University of Utah works with equipment used to detect magnetic "spins" of phosphorus atoms (photo courtsey: John Lupton/University of Utah)

A US-German team of scientists could advance a step closer to designing super fast quantum computers with their recent experiment showing how a phosphorus-and-silicon quantum computer might work. Their study to be published in the December issue of Nature Physics shows it's possible to read data stored in the form of the magnetic "spins" of phosphorus atoms. They have demonstrated experimentally that the nuclear spin orientation of phosphorus atoms embedded in silicon can be measured by very subtle electric currents passing through the phosphorus atoms.

Digital computers of the current world rely on information transmitted by flowing electricity in the form of electrons, which are negatively charged subatomic particles. Transistors in these computers are electrical switches that store data as "bits" in which "off" (no electrical charge) and "on" (charge is present) represent one bit of information: either 0 or 1. On the other hand, in a quantum computer, one quantum bit or 'qubit' could be both 0 and 1 at the same time. Quantum computers rely on the fact that the smallest particles can be in different places at the same time abiding by some seemingly strange laws of quantum mechanics.

The scientists harnessed the unique properties of quantum physics by "doping" silicon — the semiconductor used in digital computer chips — with atoms of phosphorus. Next they applied electric current to read and process the data stored in the "spins" of those phosphorous atoms' nuclei. which may register a value of 0 and 1 simultaneously. In essence, the team's study was about a successful "reading" of the net spin of 10,000 of the electrons and nuclei of phosphorus atoms near the surface of the silicon.

This is a major step in right direction but, like any other revolution in science and technology, it needs to go through lot of developments and wait for progress in other related aspects before a quantum computer becomes a reality.

Team of scientists: Christoph Boehme, University of Utah, USA; Klaus Lips at the Hahn-Meitner Institute, Berlin with graduate students Andre Stegner and Hans Huebl; Martin Stutzmann and Martin Brandt, Technical University of Munich.

Background Reading:
"
The Quantum Computer: An Introduction" by Jacob West, Caltech, USA
"Quantum computation: a tutorial" by Samuel L. Braunstein, University of York, York, UK.
Wikipedia page on quantum computer

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