Cold atoms and nanotubes come together in atomic 'black hole'
Launched laser-cooled atoms are captured by a single, suspended, single-wall carbon nanotube charged to hundreds of volts. A captured atom spirals toward the nanotube (white path) and reaches the environs of the tube surface, where its valence electron (yellow) tunnels into the tube. The resulting ion (purple) is ejected and detected, and the dynamics at the nanoscale are sensitively probed.
Carbon nanotubes, long touted for applications in electronics and in materials, may also be the stuff of atomic-scale black holes.
Physicists at Harvard University have found that a high-voltage nanotube (a tiny tubelike structure) can cause cold atoms to spiral inward under dramatic acceleration before disintegrating violently. The physicists’ experiments, which are the first to demonstrate something akin to a black hole at atomic scale, are described in the current issue of the journal Physical Review Letters.
Cold Atoms and Nanotubes Come Together in an Atomic 'Black Hole'
"On a scale of nanometers, we create an inexorable and destructive pull similar to what black holes exert on matter at cosmic scales," says Lene Vestergaard Hau, Mallinckrodt Professor of Physics and of Applied Physics at Harvard. "As importantly for scientists, this is the first merging of cold-atom and nanoscale science, and it opens the door to a new generation of cold atom experiments and nanoscale devices."
We observe the capture and field ionization of individual atoms near the side wall of a single suspended nanotube. Extremely large cross sections for ionization from an atomic beam are observed at modest voltages due to the nanotube’s small radius and extended length. The effects of the field strength on both the atomic capture and the ionization process are clearly distinguished in the data, as are prompt and delayed ionizations related to the locations at which they occur. Efficient and sensitive neutral atom detectors can be based on the nanotube capture and wall ionization processes.