Atom Chips, Attosecond Lasers Featured

New progress in "atom chips," studies of X-ray emissions in our solar system, and a town meeting to discuss the future of the field were among the highlights of the 36th annual meeting of the APS Division of Atomic, Molecular and Optical Physics (AMO), held May 17-21 in Lincoln, Nebraska.

Among the special events was an Einstein Centennial Symposium to celebrate the World Year of Physics, and a performance by "storysmith" Susan Marie Frontczak dramatizing the life of Marie Curie. Presidential Science Advisor Jack Marburger delivered the Friday evening banquet keynote address, and several of the University of Nebraska-Lincoln’s laboratories devoted to AMO physics were open for tours on Thursday evening.

Interferometer on a Chip. Scientists at the University of Colorado and JILA have succeeded in building an atom Michelson interferometer on a single "atom chip," according to Dana Z.Anderson. The chip uses lithographically patterned conductors and external magnetic fields to produce and guide a Bose-Einstein condensate.

High-Order Harmonics. According to Margaret Murnane of the University of Colorado/JILA, high-order harmonic generation (HHG) provides a useful source of coherent, ultrafast light in the extreme UV region of the spectrum. In HHG an intense laser pulse is focused into a medium, and the nonlinear interaction between the laser light and the atoms creates higher-order harmonics, resulting in a coherent, low-divergence beam.

Murnane and her colleagues have shown that by combining phase matching, quasi-phase matching, and pulse compression in a single gas-filled waveguide, they can shift the phase-matching region in large atoms to significantly higher energies. The technique has useful applications in ultrafast atomic and molecular dynamics, coherent control of electron dynamics, lithography, high-resolution imaging, site-specific spectroscopy, and bio-microscopy.

Gravity Probe B. Last April, the Gravity Probe B satellite was launched, designed to perform a high-precision test of the general theory of relativity. The instrument is currently making measurements of the precession rates of the four mechanical gyroscopes relative to the guide star, IM Pegasi. Its motion in turn is being measured relative to extragalactic reference sources. According to Stanford University’s G.M. Keiser, combining these two references will enable physicists to determine the precession rate of the gyroscopes relative to the extragalactic reference sources, which can in turn be compared with the geodetic and frame-dragging precession rates predicted by the general theory of relativity.

The X-Ray Factor. Many objects in our solar system emit X-rays, most notably the Sun, Venus, Earth, Mars, Jupiter, and comets. Thomas Cravens focused on X-ray emissions from the aurora of Jupiter, particularly the first observations of the planet by the Chandra X- Ray Observatory, which revealed a powerful X-ray aurora in the polar caps. He believes it is explained by energetic heavy ion precipitation, either on open field lines connecting to the solar wind, or on closed field lines reaching to the planet’s outer magnetosphere. NASA/GSFC’s Timothy Kallman has analyzed recent observations of X-ray spectra in nebulae surrounding hot stars and in active galaxies. It has long been known that photoionization and photoabsorption play a dominant role in determining the state of a gas in such systems, but Kallman concluded that these processes are also dominant in highly ionized gas near compact objects.

Town Meeting. Ten years after the last comprehensive assessment of the AMO field, there have been numerous significant advances that are giving rise to profound changes in AMO physics and its applications. A panel has been formed to conduct a new study, co-chaired by Philip Bucksbaum and Robert A. Eisenstein. Both men were on hand at the DAMOP meeting for Friday evening’s Town Meeting open-microphone panel discussion.