Pappalardo Fellows in Physics: Research Highlights

1. Fellowship Program Overview
   
   
2. Current Pappalardo Fellows in Physics: 2006–07 Academic Year
   
   
3. Incoming Pappalardo Fellows in Physics: 2007–10
   
   
4. Former Pappalardo Fellows in Physics
   
   
5. Pappalardo Fellowships Program Founder: A. Neil Pappalardo (EE '64)
   
   
6. Pappalardo Fellowships Competition
   
   
7. Pappalardo Fellows: Research Highlights

Pappalardo Fellows: Research Highlights

Each month, the Pappalardo Fellowships program showcases the research of one of the current Fellows. All research reports are presented in PDF format.

ARCHIVES: Pappalardo Fellows: Research Highlights

David Kielpinski 2002-05, Experimental Atomic Physics

Laser cooling and trapping are central to modern atomic physics. The low temperatures and long trapping times now routinely achieved by these means provide a suitable starting point for evaporative cooling to Bose-Einstein condensation, and can be used to initialize small ion-trap quantum computers. However, laser cooling has been demonstrated on less than 20 atomic elements; for other elements, the laser systems required are very difficult to build.

During his Pappalardo Fellowship, Kielpinski proposed a scheme to extend laser cooling to other elements using a different light-atom interaction, namely two-photon absorption of ultrafast laser pulses. An ultrafast laser produces precisely timed light pulses of duration as short as a few femtoseconds. In contrast, the usual laser-cooling system uses single-frequency lasers, which provide a steady stream of light. The use of ultrafast pulses offers technological advantages such as efficient nonlinear frequency conversion and addressing of multiple atomic transitions.

Over the past year, Kielpinski and his colleagues have constructed a ytterbium ion trap and associated laser systems for a proof-of-principle experiment on the laser cooling technique. They have successfully trapped large numbers of ions in an ultra-high vacuum chamber and detected them by fluorescence under an ultraviolet laser. This laser cools the ions to an estimated temperature of 70 K by the standard method. They've also built and characterized the femtosecond laser needed for the test of the new cooling method. Currently, they're pursuing a test of the new cooling method.

A successful proof of principle experiment in the ion trap will be followed by an effort to laser cool hydrogen by the new technique. Efficient laser cooling of hydrogen would offer impressive gains in atomic clocks and measurements of fundamental constants, but has remained technically intractable. Laser-cooling the low-energy antihydrogen recently produced at CERN could lead to a precise test of the Standard Model by comparing hydrogen and antihydrogen clock frequencies.

[top]