Since these Cooper pairs are both pure quantum states and macroscopic, it is easier to see real quantum states than with microscopic states, and relatively easy to build applied quantum devices.
Since these Cooper pairs are both pure quantum states and macroscopic, it is easier to see real quantum states than with microscopic states, and relatively easy to build applied quantum devices.
Brian Josephson, while a Cambridge undergraduate, realized one could observe interference between two Cooper pairs in a macroscopic junction tunneling between two superconducting metal samples.
As the phase is changed between the two pairs, for example by putting on a small magnetic field, the tunneling rate changes in an oscillatory way: