An apparatus and method, the apparatus comprising: a layer of quantum tunnelling composite configured such that in a non-compressed state the quantum tunnelling composite is an electrical insulator and in a compressed state the layer of quantum tunnelling composite is an electrical conductor; a magnetic portion configured to cause compression of the quantum tunnelling composite; and wherein the apparatus is configured to be coupled to a reciprocal apparatus where the reciprocal apparatus comprises a reciprocal magnetic portion such that when the apparatus is coupled to the reciprocal apparatus the magnetic portion causes compression of the quantum tunnelling composite to provide a direct current path through the quantum tunnelling composite to the reciprocal apparatus.