  Atomic physics can probe the Lorentz and CPT symmetries at the Planck level.
Bounds on coefficients for Lorentz violation have been found using atomic
clocks, masers, electromagnetic cavities, and Penning traps, among others, and
in future it may be possible to place bounds using spectroscopy of antihydrogen
atoms. The CPT '04 Meeting on CPT and Lorentz Symmetry was held in August 2004
in Bloomington, Indiana, USA, and covered Lorentz violation in all branches of
physics. This report gives an overview of the recent advances in
Lorentz-symmetry studies in atomic and optical physics.
