Experiment to detect frame dragging in a lead superconductor

Recent work by Tajmar and de Matos predicts a greatly enhanced gravitomagnetic field is measurable in the vicinity of a rotating superconductor. They predict that the associated frame dragging is measurable when the density of Cooper pairs is sufficiently large relative to the mass density. Experimental measurements with superconducting lead and niobium samples reported by the same group support this theory. We have conducted an experiment with superconducting lead and a very large ring laser gyroscope. No frame dragging effect was observed by us. We find that if the effect exists it is at least 22 times smaller than predicted by the theory, otherwise it would have been detected in our experiment with probability ⩾95%.