  Cosmological observations as well as theoretical approaches to physics beyond
the Standard Model provide strong motivations for experimental tests of
fundamental symmetries, such as CPT invariance. In this context, the
availability of cold baryonic antimatter at CERN has opened an avenue for
ultrahigh-precision comparisons of protons and antiprotons in Penning traps.
This work discusses an experimental method inspired by quantum logic techniques
that will improve particle localization and readout speed in such experiments.
The method allows for sympathetic cooling of the (anti-)proton to its
quantum-mechanical ground state as well as the readout of its spin alignment,
replacing the commonly used continuous Stern-Gerlach effect. Both of these
features are achieved through coupling to a laser-cooled `logic' ion co-trapped
in a double-well potential. This technique will boost the measurement sampling
rate and will thus provide results with lower statistical uncertainty,
contributing to stringent searches for time dependent variations in the data.
Such measurements ultimately yield extremely high sensitivities to CPT
violating coefficients acting on baryons in the Standard-Model Extension, will
allow the exploration of previously unmeasured types of symmetry violations,
and will enable antimatter-based axion-like dark matter searches with improved
mass resolution.
