Broadband laser cooling of trapped atoms with ultrafast pulses

We demonstrate broadband laser cooling of atomic ions in an rf trap using ultrafast pulses from a mode-locked laser. The temperature of a single ion is measured by observing the size of a time-averaged image of the ion in the known harmonic trap potential. Although the lowest observed temperature was only about 1 K, this method efficiently cools very hot atoms and can sufficiently localize trapped atoms to produce near diffraction-limited atomic images. (c) 2006 Optical Society of America.