Think of this experiment as the smallest particle accelerator in the world: atoms spiral along a carbon nanotube electrically charged, suffered a dramatic acceleration until disintegrating violently.
Physicists at Harvard University who discovered the phenomenon say that besides being promising for the area of electronics and possibly even to build a space elevator , carbon nanotubes may also be the basis for the generation of black holes microscopes.
They found that a carbon nanotube electrically charged, super-cold atoms can enter into a spiral motion around them, speeding up rapidly disintegrating, without having to collide with each other.
Atomic black hole
The experiment was the first to show something similar to a black hole at the atomic scale, earned the cover of the journal Physical Review Letters, the most important scientific journal in the world of physics.
“On a scale of nanometers, we create an attraction similar to the inexorable and destructive that black holes exert on the matter on cosmic scales,” says Lene Vestergaard Hau, coauthor of the research.
Professor Lene Hau became famous worldwide in creating the first experiments able to stop light . His experiences also formed the basis for other scientists to capture the “nothing” , or at least what physicists call vacuum condensate.
“Besides being extremely important to scientists, this is the first merger between the physics of cold atoms and nanoscience, opening the door to a new generation of experiments of cold atoms and nanoscale devices,” she envisions.
The carbon nanotube single-wall – his wall is formed by a single layer of carbon atoms – was built over a gap of 10 micrometers in width of a silicon chip using a process called chemical vapor deposition.
The chip provides both mechanical support and the electrodes through which the carbon nanotube can be energized.
Thus, although it is hollow, the nanotube in this experiment acted as a carbon nanowire, where the atoms do not have a route by which to immerse yourself directly in its interior.
“From the standpoint of the atom, the nanotube is infinitely long and thin, creating a unique effect on the atom,” says Hau.
Hau and her colleagues used lasers to cool clouds containing a million rubidium atoms to a fraction of a degree above absolute zero.
Then they threw the atomic cloud – which has a length in the range of millimeters – toward the suspended carbon nanotube, which was located about two inches apart and loaded with hundreds of volts.
The vast majority of atoms passed straight through the nanowire, but those who came to him about one micrometer were inevitably drawn, entering a spiral motion around and reaching high speeds, accelerated by the voltage of the nanotube.
“From an initial speed of about 5 meters per second, the cold atoms reached speeds of about 1,200 meters per second, or nearly 4,500 mph, as it revolved around the nanotube,” says Anne Goodsell, co-author of the study.
“As part of this tremendous acceleration, the temperature corresponding to the kinetic energy of atoms increased from 0.1 Kelvin to thousands of degrees Kelvin in less than a microsecond,” adds Goodsell.
Physical and Nanosciences
At this point, the fast atom disintegrated into an electron and an ion, both revolving around the nanowire parallel, each completing one orbit in just a few trillionths of a second.
The electron is eventually sucked into the nanotube by means of quantum tunneling , causing his partner ion is thrown away – repelled by the strong electrical charge of the nanotube 300 volts – at a speed of about 26 kilometers per second, almost 95,000 kilometers per hours.
The accuracy achieved by the experiment, allowing the monitoring of both the atoms and the processes at the nanoscale, including the tracking of atoms, electrons and dynamics of ions, was only possible thanks to a novel junction between physics and nanoscience.
Field Ionization of Cold Atoms near the Wall of the Single Carbon Nanotube
Anne Goodsell, Trygve Ristroph, Jene A. Golovchenko, Lene Vestergaard Hau
Physical Review Letters
Vol: 104, 133002 (2010)