Synopsis: Ionizing atoms with a nanotube

A single carbon nanotube held at a positive voltage can capture and ionize individual cold atoms with high efficiency.
Synopsis figure
Illustration: Courtesy of A. Goodsell et al.

The extremely large electric fields that can be produced near the tips of carbon nanotubes suggests their potential use as electron field emission sources for low-power video displays or as highly sensitive gas detectors. But nanotubes often come in macroscopic bunches of irregular length whose electric field is difficult to characterize and whose geometry is not optimized for efficient ionization of atoms.

In a recent paper published in Physical Review Letters, Anne Goodsell, Trygve Ristroph, Jene Golovchenko, and Lene Vestergaard Hau from Harvard University, US, have used the side wall, rather than the tip, of a single charged carbon nanotube to ionize individual ultracold atoms, which they detected one-by-one. Using the field from the entire wall of a tube gives a much higher likelihood of “capture,” as does the use of slow-moving, ultracold atoms.

In the experiment by Goodsell et al., a cloud of neutral rubidium atoms cooled to 200μK is launched upward toward a charged nanotube that lies horizontally across a 10-μm-wide hole in a silicon structure. The nanotube polarizes atoms nearby, and an atom within a threshold distance spirals rapidly toward the wall. Eventually an electron tunnels from the atom to the tube, creating an ion that is ejected and measured by a detector.

The experiment combines nanotechnology with cold atoms to demonstrate a new type of high-resolution, single-atom, chip-integrated detector that may ultimately be able to resolve fringes from the interference of matter waves. The authors also foresee a range of single-atom, fundamental studies made possible by their setup. – David Ehrenstein


Features

More Features »

Subject Areas

Atomic and Molecular Physics

Previous Synopsis

Magnetism

Pressed to order

Read More »

Next Synopsis

Related Articles

Synopsis: A Dark Side for Qubits
Quantum Information

Synopsis: A Dark Side for Qubits

Dark solitons in a Bose-Einstein condensate could, according to calculations, function as qubits with long lifetimes. Read More »

Viewpoint: Measuring the Tidal Force on a Particle’s Matter Wave
Gravitation

Viewpoint: Measuring the Tidal Force on a Particle’s Matter Wave

The effect of the tidal force, which is directly related to the curvature of spacetime, on an individual particle’s wave function has been measured with an atom interferometer. Read More »

Synopsis: Cooling Multiple Atoms in a Cavity
Atomic and Molecular Physics

Synopsis: Cooling Multiple Atoms in a Cavity

A cavity-based method of cooling single atoms or other objects has now been used to cool multiple atoms simultaneously. Read More »

More Articles