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 1K, this method efficiently cools very hot atoms and can sufficiently localize trapped atoms to produce near diffraction-limited atomic images.