  The neutral-kaon system constitutes a fantastic and unique laboratory for the
study of CPT symmetry and the basic principles of quantum mechanics, and a
$\phi$-factory represents a unique opportunity to push forward these studies.
The experimental results show no deviation from the expectations of quantum
mechanics and CPT symmetry, while the extreme precision of the measure- ments,
in some cases, reaches the interesting Planck-scale region. At present the
KLOE-2 experiment is collecting data with an upgraded detector with the aim of
significantly improving these kinds of experimental tests.
