APS News

''Ionic Waltz'', Ultrafast Lasers Highlight 2003 DAMOP Meeting

The best measurement to date testing Einstein's theory of special relativity, ultrafast lasers, and a measurement of the speed of information were among the highlights at the 34th annual meeting of the APS Division of Atomic, Molecular and Optical Physics (DAMOP), held in Boulder, Colorado, May 20-24, 2003. The meeting also featured a special public lecture by magician and professional debunker James Randi.

Waltzing Ions Test Relativity. MIT physicists have improved on the world's most accurate mass comparisons by a factor of 10. They achieved this by performing simultaneous cyclotron frequency com- parisons of two ions in a Penning trap. The group used the technique to measure the energy-to-mass conversion in a nuclear reaction, providing a new type of test of Einstein's special relativity.

Lasers That Learn. Ultrafast strong lasers are revolutionizing atomic, molecular and optical physics, according to Philip Bucksbaum of the University of Michigan, Ann Arbor, who discussed new developments in the field. These lasers, which create the shortest pulses of light ever, are able to monitor chemical reactions in progress and control how molecules interact. To achieve their remarkable results, the lasers use "learning loops"?algorithm-based feedback loops that discover and create unusual optical pulse shapes?to control the chemical, electronic or physical dynamics of matter.

The Fast and the Furious. At the DAMOP meeting, a group from Duke University presented the results of their experiments to directly test the speed of information. They constructed a medium with anomalous dispersion consisting of a vapor of laser-driven potassium atoms, employing a novel experimental geometry to suppress competing nonlinear optical effects. The group observed a pulse with a smooth Gaussian-shaped envelope that is advanced by as much as 20% with little distortion in comparison to an identical pulse traveling through a vacuum. They were also able to create an alphabet of pulse shapes and explore how each "letter" propagates through the medium to determine the information velocity.

The Ancient Life of Water. Using a new technique, researchers are able to date ancient water up to one million years old, providing vital information for understanding geological processes. The new test uses a magneto-optical trap to analyze a mere 100 microliters of krypton-81 gas. Researchers have collected krypton from the Nubian Aquifer underneath the Eastern Sahara Desert, and presented the dating results of their samples at the meeting.

Better Magnetic Brain Scans. MRI is the best technique we have for precisely mapping the brain. But researchers at the University of Washington and Princeton University have now developed a more accurate device for measuring the tiny magnetic fields in the brain: a new atomic magnetometer with a sensitivity that far surpasses the performance of current SQUID devices. Representatives from the collaboration discussed how the device can be used for improving medical imaging.

Probing Atoms with Telescopes. The best large aperture telescopes with their high-precision instruments are able to probe the properties of atoms and molecules as well as laboratory experiments. An added advantage is that they can perform measurements on particles that are not able to be studied in the lab, such as the atomic nitrogen transitions, which have never been detected in the laboratory and only rarely in the atmosphere. Thanks to the efforts of researchers at SRI International and Vanderbilt University, this technique has been the first to measure certain properties of atmospheric nitrogen and other molecules.

Building a Better Atomic Clock. The most precise measurements of time come from atomic clocks and are critically important for advanced telecommunications and other high-tech applications. However, the most precise atomic clocks are bulky devices. At the DAMOP meeting, two groups presented their progress in making miniature atomic clocks. A group at NIST in Boulder, Colorado, has devised a scheme for ultra- small physics packages for atomic frequency references based on coherent population trapping resonances in alkali vapors. Another group at Princeton University is investigating the advantages of operating a miniature optical atomic clock using the "end" transitions, or connecting states, of rubidium-87 atoms; most traditional atomic clocks are based on the hyperfine transition of Cesium-133 atoms.

What Makes a Good Physics Department? The National Task Force on Undergraduate Physics has just completed a survey of all 759 bachelors-degree-granting physics programs in the US and site visits of 21 leading departments. According to Robert Hilborn (Amherst College), the study reveals that thriving physics departments feature energetic leadership, involvement of most faculty in undergraduate teaching, a challenging but supportive curriculum, many opportunities for informal student-faculty interactions, flexible programs, career mentoring and a strong sense of community shared by faculty and students.

In a separate session, a group from Colorado College discussed how physics departments have successfully attracted higher participation by women in undergrad- uate programs. The critical factor is a strong female-friendly departmental culture that reaches out to include students in the introductory course.

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Editor: Alan Chodos
Associate Editor: Jennifer Ouellette