Antiproton Trapping for 614 days

Abstract We report the trapping and continuous monitoring of a cloud of antiprotons (\pbar{}) for 614 days in the BASE reservoir trap at CERN, representing the longest confinement of antimatter achieved to date. The experiment is operated at an exceptionally low particle-loss rate of less than one antiproton per month, with intervals approaching up to five months without a single loss, and demonstrating one year of continuous experiment operation within which only three particles were consumed. This unprecedented stability establishes a new paradigm for high-precision studies of exotic and ultra-rare charged particles. Our approach is readily extendable to other species, including highly charged ions and prospective antimatter systems such as $\overline{\mathrm{H}}_2^-$, $\overline{\mathrm{H}}^+$, and $\overline{\mathrm{d}}$. By analyzing all BASE reservoir trap data collected since 2014, we set a five-fold improved lower bound on the directly constrained antiproton lifetime. Beyond its fundamental implications, this advance enables future transport and precision measurements on \pbar{} and other exotic ions in dedicated offline laboratories, opening new frontiers in antimatter research.