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Why the resistance in superconductors is zero? I know the BCS cooper pair formation but why in principle it behaves like that?

Qmechanic
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Rick Andy
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1 Answers1

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DC Resistance in ordinary conductors is caused by the conduction electrons colliding with the conductor's ions and various other imperfections in the conductor.You're asking why superconductors are impervious to all these collisions.

The reason why Cooper Pairs change things isn't the pairing per se, but the fact that the pair together acts as a boson, and thus all these bosons can share the same ground state (a so-called Bose–Einstein Condensate). Since they are already at the ground state, there is no way for them to loose more energy during a collision. Moreover, because the state energies are discrete, there is a non-zero energy gap between this ground state and the next state, so if a collision were to add some energy which is lower than this gap, this energy can't be added to the pair, and basically the collision doesn't happen and the pair continues on its merry way, uncollided.

Nadav Har'El
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