Testing CPT violation, entanglement and gravitational interactions in particle mixing with trapped ions Antonio Capolupo, Salvatore Marco Giampaolo and Aniello Quaranta Eur. Phys. J. C, 81 5 (2021) 410 Published online: 11 May 2021 DOI: 10.1140/epjc/s10052-021-09194-6