Precision tests of quantum mechanics and $$ \mathcal{CPT} $$ symmetry with entangled neutral kaons at KLOE

Abstract

The quantum interference between the decays of entangled neutral kaons is studied in the process ϕ → KSKL → π+π−π+π−, which exhibits the characteristic Einstein-Podolsky-Rosen correlations that prevent both kaons to decay into π+π− at the same time. This constitutes a very powerful tool for testing at the utmost precision the quantum coherence of the entangled kaon pair state, and to search for tiny decoherence and $$ \mathcal{CPT} $$ CPT violation effects, which may be justified in a quantum gravity framework.The analysed data sample was collected with the KLOE detector at DAΦNE, the Frascati ϕ-factory, and corresponds to an integrated luminosity of about 1.7 fb−1, i.e. to about 1.7 × 109ϕ → KSKL decays produced. From the fit of the observed ∆t distribution, being ∆t the difference of the kaon decay times, the decoherence and $$ \mathcal{CPT} $$ CPT violation parameters of various phenomenological models are measured with a largely improved accuracy with respect to previous analyses.The results are consistent with no deviation from quantum mechanics and $$ \mathcal{CPT} $$ CPT symmetry, while for some parameters the precision reaches the interesting level at which — in the most optimistic scenarios — quantum gravity effects might show up. They provide the most stringent limits up to date on the considered models.

Precision tests of Quantum Mechanics and CPT symmetry with entangled neutral kaons at KLOE

“…The obtained results [6] are more than twice improved with respect to previous KLOE results [7] and are consistent with no decoherence and no CPT violation.…”

“…The models briefly mentioned above are fit to the data distribution of the difference of the kaon decay times measured with the KLOE detector to obtain values of the defined parameters. The analysis is based on a data sample [6] four times larger and statistically independent with respect to the previous KLOE measurement [7]. An improved background and signal selection are performed.…”

Observation of the post-tagging effect for entangled K mesons at KLOE

“…The experimental resolution effects on 1 and 2 times are taken into account with a smearing matrix obtained from a Monte Carlo simulation, similarly to the decoherence analysis presented in Ref. [5]. The backgrounds from the non-resonant + − → 4 process and from kaon regeneration on the beam pipe are negligible [5].…”

Can future observation of the living partner post-tag the past decayed state in entangled neutral K mesons?

“…Several tests of quantum mechanics and searches for possible decoherence and CPT violation effects that can exploit strange entanglement of neutral kaons have been proposed . The experimental investigation of strange entanglement started with the CPLEAR experiment [39] and continued with the KLOE and KLOE-2 experiments [40][41][42] at DAΦNE [43][44][45], yielding several precision results [46][47][48][49][50][51][52][53][54].…”