  Neutral kaons produced in correlated pairs at a phi-factory offer unique
possibilities to perform fundamental tests of CPT invariance, as well as of the
basic principles of quantum mechanics. The analysis of the data collected by
the KLOE experiment at DAFNE is still ongoing with the aim of improving
previous results and limits on several parameters describing CPT violation and
decoherence. Ancillary measurements like the regeneration cross section on the
beam pipe materials are also in progress and will be very useful to reduce the
systematic uncertainties. Prospects on improvements at the KLOE-2 experiment,
aiming at an increase of the integrated luminosity of about a factor of ten
with an upgraded detector, will be also discussed.
