Recent experiments with positronium in LHe could be the first step in this line of research, in this case being able to stabilize antimatter may lead eventually to a way for its properties to be studied, specifically its properties in a gravitational field. It has been suggested that a material capable of holding a proton/antiproton pair in the same way might be more useful as protons are substantially more massive than electrons and any gravitational effects would be magnified by several orders of magnitude up to a point where detection is trivial using a cooled accelerometer or other quantum displacement sensor.