Rashba Splitting of Cooper Pairs.
We investigate theoretically the properties of a weak link between two superconducting leads, which has the form of a nonsuperconducting nanowire with a strong Rashba spin-orbit coupling caused by an electric field. In the Coulomb-blockade regime of single-electron tunneling, we find that such a weak link acts as a "spin splitter" of the spin states of Cooper pairs tunneling through the link, to an extent that depends on the direction of the electric field. We show that the Josephson current is sensitive to interference between the resulting two transmission channels, one where the spins of both members of a Cooper pair are preserved and one where they are both flipped. As a result, the current is a periodic function of the strength of the spin-orbit interaction and of the bending angle of the nanowire (when mechanically bent); an identical effect appears due to strain-induced spin-orbit coupling. In contrast, no spin-orbit induced interference effect can influence the current through a single weak link connecting two normal metals.
Department of Physics, University of Gothenburg, SE-412 96 Göteborg, Sweden.
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Shekhter
Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel.|Physics Department, Ben Gurion University, Beer Sheva 84105, Israel.
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Entin-Wohlman
Department of Physics, University of Gothenburg, SE-412 96 Göteborg, Sweden.|SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
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Jonson
Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel.|Physics Department, Ben Gurion University, Beer Sheva 84105, Israel.
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Aharony