Progress towards an improved comparison of the proton-to-antiproton charge-to-mass ratios

High-precision comparisons of the proton-to-antiproton charge-to-mass ratios provide sensitive tests of the fundamental charge, parity, time (CPT) invariance. In 2014, we performed such a measurement with a fractional precision of 69parts in a trillion (p.p.t.). In this article, we describe technical developments which were implemented to improve the precision of our previous measurement by at least a factor of 3.