- TL;DR Summary
- The BCS theory of superconductivity assumes creation and annihilation of Cooper pairs due to temperature fluctuations below Tc. This recombination process should unavoidably destroy an initial supercurrent. However, in experiments the supercurrent is insensitive to temperature fluctuations and exists forever. How to solve the contradiction of theory/experiment?
In the BCS theory the Cooper pair density depends on temperature, meaning that pairs can be created/annihilated by temperature variations. Obviously, momenta of annihilated pairs dissipate on the atom lattice, so an initial supercurrent dissipates. On the other hand, in some experiments a supercurrent, once excited, runs for many years despite any temperature fluctuations below Tc, indicating that any pair annihilation doesn’t take place. How to solve the contradiction of theory/experiment?