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Name: Aaron Dahl
Gender: Male
Hometown: St. Louis, MO
Home country: USA
Member since: Thu May 10, 2012, 12:23 PM
Number of posts: 763

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Breakthru in quantum computing: salty nanoscale bar magnets!

Three of the big obstacles to quantum computing have been scale (teensy), temperature (cooold), and identifying materials with controllable quantum states. This salt apparently will help researchers learn more about this last problem - perhaps the most pernicious of the three. Here's some of the more telling snippets:


The international team of researchers led from the Laboratory for Quantum Magnetism (LQM) in Switzerland and the London Centre for Nanotechnology (LCN), found that the material, a transparent salt, did not suffer from the usual complications of other real magnets, and exploited the fact that its quantum spins -- which are like tiny atomic magnets -- interact according to the rules of large bar magnets. The study is published in Science.
The team were able to image all the spins in the special salt, finding that the spins are parallel within pairs of layers, while for adjacent layer pairs, they are antiparallel, as large bar magnets placed adjacent to each other would be. The spin arrangement is called "antiferromagnetic." In contrast, for ferromagnets such as iron, all spins are parallel.

By warming the material to only 0.4 degrees Celsius above the absolute "zero" of temperature where all classical (non-quantum) motion ceases, the team found that the spins lose their order and point in random directions, as iron does when it loses its ferromagnetism when heated to 870 Celsius, much higher than room temperature because of the strong and complex interactions between electron spins in this very common solid.

The team also found that they could achieve the same loss of order by turning on quantum mechanics with an electromagnet containing the salt. Thus, physicists now have a new toy, a collection of tiny bar magnets, which naturally assume an antiferromagnetic configuration and for which they can dial in quantum mechanics at will.
"While this may seem esoteric, there are deep connections between what has been achieved here and new types of computers, which also rely on the ability to tune quantum mechanics to solve hard problems, like pattern recognition in images."
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