Friday, April 9, 2010

Atom-grabbing 'black hole' created

http://www.newscientist.com/article/dn18758-atomgrabbing-black-hole-created.html: "A team led by Lene Hau of Harvard University has mimicked the death spiral of matter falling into a cosmic black hole by applying a voltage across a carbon nanotube – a rolled-up sheet of carbon atoms. This created a powerful electric field that tugged at nearby rubidium atoms, which had been chilled to a fraction of a degree above absolute zero: a positive charge on the surface of the nanotubes attracts the rubidium atoms' electrons, while the positively charged nucleus is repelled.

This polarisation causes the atoms to spiral towards the nanotube, speeding them up until the atoms circle it in just a few trillionths of a second. Eventually each atom's outermost electron detaches and enters the nanotube through a process called quantum tunnelling. The positively charged rubidium ion that it leaves behind is repelled by the positively charged nanotube and slingshots away.

Modifications to this set-up could produce a trap capable of keeping a cloud of cold atoms spinning around the nanotube. "One could use the system to make completely new states of cold atom matter," says Hau. It could also be used to detect trace amounts of gas, or be adapted to make precise atom interferometers, which measure small variations in gravity, she says."

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