Integrated Atom Optics

What electrons are for electronics and photons are for photonics, neutral atoms will be for some future "atom-tronics." That is, chilled trapped atoms will be manipulated on or near a planar microchip in such a way as to process information, especially if atoms in their wavelike manifestation can be brought into interference with each other.

In recent years there have been many advances in this hot research area: atoms have been guided along wires (Update 416, ), through waveguides (Update 469), and steered around (and slightly above) a microchip under the influence of patterned currents in the nearby surface (Update 486). And as for atom interferometry, it has been used to measure previously unknown scattering properties of matter waves (Update 209), detect subtle changes in gravitational gradients (Update 384), and used to demonstrate the wave properties of C-60 molecules (Update 453).

Three new innovations come from labs in Germany, Austria, and France. Joerg Schmiedmayer (49-622-154-9325, joerg.schmiedmayer@physl.uni-heidelberg.de) of the University of Heidelberg (recently moved from the University of Innsbruck) and his colleagues have achieved essentially a planar beamsplitter by guiding atoms a few microns above a microstructured surface (an Atom Chip) along a Y-shaped magnetic wave guide (see Physics News Graphics). Depending on how current is sent through the Y, atoms can be directed either to the left arm, to the right arm, or to both output arms with any desired ratio. By the way, the atoms themselves can be positioned with 100-nm control (the accuracy of the nanofabrication techniques) and can be made to sort of go around bends; as with light in fibers, there is some loss of atoms if their trajectory is bent too sharply (Cassettari et al., Physical Review Letters, 25 December 2000).

Another group, at the Max Planck Institute in Munich, moves atom clouds around and above a lithographic conductor pattern on a wafer, what they call a "magnetic conveyor belt." Unlike a guide, the conveyor belt transports atom clouds (800 nm across) in separate potential wells, keeping them confined in all three dimensions, allowing velocity control and ultra-precise positioning. The conveyer belt would be useful for doing interferometry experiments (especially if Bose-Einstein condensates could be transported), for "atomic ink jet printing," and as part of some future "atom coupled device," which would use atoms for performing measurements much as charge coupled devices (CCD) use electrons for imaging light fields (Hansel et al., upcoming article in Physical Review Letters; Wolfgang Hansel, wolfgang.haensel@mpq.mpg.de, 49-892-180-3937).

Meanwhile at the University of Paris-South, Laurence Pruvost (33-169-35-2100, laurence.pruvost@lac.u-psud.fr) and her students have generated a beam of guided rubidium atoms from a magneto-optic trap (MOT). The atoms are shepherded by the electric fields of a laser beam. The atoms then meet with a second beam of laser light at an oblique angle. The crossed laser beams generate two collimated atom beams making an angle of 7 degrees. Because the beamsplitter is energy selective, it might be used to help evaporate atoms of higher energy from clouds in an atom trap (Houde et al., Physical Review Letters, 25 Dec.) Cassettari et al. and Houde et al. are available at Physics News Select Article; Hansel et al. is not yet in pdf format but we can fax it to you.