One of the most fascinating and fundamentally important properties of superconductivity is its quantum behavior over large distances. Usually quantum mechanical effects are only important at low temperatures and over distances on the atomic scale, that is about 10-9 meters. Superconductors are an exception to this rule. As long ago as the late 1940s, Fritz London, with a great leap of the imagination suggested that for superconductors, the wave-particle duality should be able to be seen in vastly larger objects, even to a mile long superconducting loop.