An artificial 鈥渂lack hole鈥� designed to capture wayward atoms has been created. It paves the way for an atom trap that could yield previously unknown states of matter.
A team led by of Harvard University has mimicked the death spiral of matter falling into a cosmic black hole by applying a voltage across a carbon nanotube 鈥� 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鈥� 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鈥檚 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.
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Modifications to this set-up could produce a trap capable of keeping a cloud of cold atoms spinning around the nanotube. 鈥淥ne could use the system to make completely new states of cold atom matter,鈥� 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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