Atom optics involves the manipulation of neutral atoms in ways analogous to the ways in which light is manipulated in ordinary optics - through use of analogues for lenses, mirrors, beamsplitters, gratings, etc. Atom lenses have been our main concentration, because of their potential for focusing atoms into very small regions. While neutral atoms can be focused by static electric or magnetic fields, provided there is a gradient present, the most versatile approach has proven to be the use of resonant interaction with laser light. If a neutral atom has a strong transition, near to which a laser can be tuned, the result is a relatively strong force on the atom and an ensuing change in its trajectory. This force has two distinct origins, either through repeated absorption and spontaneous emission of photons, or through an induced AC electric dipole moment interacting with a gradient in the laser electric field, or intensity.
Laser light has an advantage when it comes to focusing atoms on the nanometer scale.
Because of interference phenomena, such as a standing wave, intensity gradients can be formed over extremely small regions, approaching half the wavelength of the light, or a few hundred nanometers. Thus the size of the lens that focuses the atoms is already close to the nanometer scale, allowing atoms to be focused to dimensions much smaller. While these gradients extend over very small regions, the overall pattern can cover a very large area of a substrate. We have exploited these properties of laser light to focus chromium atoms into a series of lines or dots with feature size as small as 38 nm, covering areas as large as 0.4 mm by 1 mm. Current work, as discussed in the various project descriptions, is involved in extending the capabilities to encompass improving resolution, generating more complex patterns, nanofabricating with materials other than Cr, and investigating various applications of the fabricated structures.