Experiments on the violation of electromagnetic gauge symmetry by Yang–Mills gravity using Josephson effects in superconductors

Yang–Mills gravity is a quantum theory of gravity with translational gauge symmetry that is based on a flat spacetime. The universal coupling of all quantum fields to quantum Yang–Mills gravity is based on the replacement of [Formula: see text] by the translational gauge covariant derivative [Formula: see text] in the Lagrangians of non-gravitational fields. Near the surface of the Earth, Yang–Mills gravity causes the phase gradient [Formula: see text] to be altered by a factor of [Formula: see text]. In addition, the usual gauge-invariant combination of phase gradients and electromagnetic vector potentials [Formula: see text] in Josephson junctions is modified and is no longer [Formula: see text] gauge invariant. The voltage across a Josephson junction is thus affected by the presence of the gravitational coupling constant g, and is now given by [Formula: see text]. If one were to compare the voltage across a Josephson junction in a laboratory at rest on Earth with that across a junction in free fall (e.g. in the International Space Station), Yang–Mills gravity predicts a difference on the order of 1 part in [Formula: see text], which should be detectable as the precision of the Josephson junction voltage standard is on the order of a few parts in [Formula: see text]. Measurements of two terms in [Formula: see text] can test (i) the gravitational effect on the Josephson voltage-phase relation, and (ii) the violation of the [Formula: see text] gauge symmetry in superconductors by Yang–Mills gravity.