Cooper pair
= Cooper pair
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A Cooper pair is a correlated pair of <fermions> associated with <superconductivity>. The conventional <BCS ground state> uses opposite-momentum, opposite-spin pair creation operators $c_{k\uparrow}^\dagger c_{-k\downarrow}^\dagger$. Their total momentum is zero for every relative momentum $k$; zero total momentum does not restrict $k$ to zero.