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First Bose-Einstein condensation of strontium
Posted by wideant in Quantum Physics on March 19, 2010
In an international first, scientists from the Institute of Quantum Optics and Quantum Information (IQOQI, Austria) produced a Bose-Einstein condensate of the alkaline-earth element strontium, thus narrowly winning an international competition between many first-rate scientific groups. Choosing the isotope 84Sr, which has received little attention so far, proved to be the right choice for the breakthrough. It can now be regarded as an ideal candidate for future experiments with atomic two-electron systems.
This is not the first time that Prof. Rudolf Grimm and his scientific team have won a tightly contested race between scientists: in 2002, they were the first to produce a Bose-Einstein condensate of cesium atoms. Read the rest of this entry »
Straightening messy correlations with a quantum comb
Posted by wideant in Quantum Physics on March 2, 2010
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 business. Now two physicists have shown, mathematically, how to gently tease out unwanted knots in quantum communication, while keeping the information intact. Their work is reported in the current issue of Physical Review Letters and highlighted with a Viewpoint in Physics.
When two particles are entangled, they effectively act as a single entity, even though they might be on opposite ends of the galaxy. Physicists can code information into particles to make quantum bits, or qubits, then entangle the qubits in an orderly fashion to form an entangled bit, or ebit. Ebits can then be used to create incredibly tough codes or teleport information between two distant systems. But messy entanglements among particles make qubits more susceptible to losing their encoded information. Read the rest of this entry »
Rewriting general relativity? Putting a new model of quantum gravity under the microscope
Posted by wideant in Quantum Physics on March 1, 2010
Does an exciting but controversial new model of quantum gravity reproduce Einstein’s theory of general relativity? Scientists at Texas A&M University in the US explore this question in a paper appearing in Physical Review Letters and highlighted with a Viewpoint in the August 24th issue of Physics.
“If it ain’t broke, don’t fix it,” sums up fairly well how many scientists have viewed Einstein’s theory of general relativity. The theory, which Einstein developed in the early 20th century, says that matter curves spacetime, and it is this curvature which deflects massive bodies – an effect that we interpret as the influence of gravity. The theory has been tested to extremely high accuracy and without it, our satellite global positioning system would be off by about 10 km per day. Read the rest of this entry »