We investigate entanglement of two electron spins forming Cooper pairs in an s -wave superconductor. The two-electron space-spin density matrix is obtained from the BCS ground state using a two-particle Green's function. It is demonstrated that a two spin state is not given by a spin singlet state but by a Werner state. It is found that the entanglement length, within which two spins are entangled, is not of the order of the coherence length but of the order of the Fermi wave length.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 15 Dec 2005|
ASJC Scopus subject areas
- Condensed Matter Physics