Production of non-local quartets and phase-sensitive entanglement in a superconducting beam splitter
Abstract
Three BCS superconductors Sa, Sb, and S and two short normal regions Na and Nb in a three-terminal SaNaSNbSb set-up provide a source of non-local quartets spatially separated as two correlated pairs in Sa and Sb, if the distance between the interfaces NaS and SNb is comparable to the coherence length in S. Low-temperature dc-transport of non-local quartets from S to Sa and Sb can occur in equilibrium, and also if Sa and Sb are biased at opposite voltages. At higher temperatures, thermal excitations result in correlated current fluctuations which depend on the superconducting phases phia and phib in Sa and Sb. Phase-sensitive entanglement is obtained at zero temperature if Na and Nb are replaced by discrete levels.
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