Figure 1
Illustration: Alan Stonebraker

Figure 1: An example of how coupling a superconductor to a metal can enhance superconductivity. The left panel shows a Josephson junction array: a set of superconducting islands (gold squares) that are separated by insulating material (blue substrate). When the energy to add or remove one Cooper pair (two bound electrons) on a single island is large compared to the energy gained by allowing the electrons to move throughout the entire array, the Cooper pair wave functions (gray curves) are localized and do not have a well defined phase. Capacitively coupling the array to a metal (right panel) damps the fluctuations in the Cooper pair wave functions and they condense into a single superconducting state.