Fig. 1
From: Proposal for a quantum mechanical test of gravity at millimeter scale
The experimental setup for testing gravity via a Josephson junction. A tungsten cylinder with diameter and height 2R serves as a gravitational source and a JJ is put nearby. The distance from the midpoint of superconductor 1 inside JJ and the cylinder surface is d. The average distance between two superconductors is \(\delta\), which is equal to the size of the superconductor in the limit of a very thin insulator.
