Quaternion-Loop Quantum Gravity
  It is shown that the Riemannian curvature of the 3-dimensional hypersurfaces in space-time, described by the Wilson loop integral, can be represented by a quaternion quantum operator induced by the SU(2) gauge potential, thus providing a justification for quaternion quantum gravity at the Tev energy scale. 
M. D. Maia, S. S. e Almeida Silva, F. S. Carvalho