The entanglement in the neutral kaon pairs observed by the KLOE experiment at the DA$\Phi$NE $\phi$-factory is a unique tool to test discrete symmetries and quantum coherence at the utmost sensitivity, in particular strongly motivating the experimental searches of possible CPT violating effects, which would unambiguously signal New Physics.\newline
We will present the final result of the measurement of the decoherence and CPT violation parameters in $K_S K_L \rightarrow \pi^+ \pi^- \pi^+ \pi^-$ with an improved statistical accuracy of a factor $\sim 2$ with respect to literature.
