Crossed Andreev reflection in InSb flake Josephson junctions
F.K. de Vries (TU Delft - QRD/Goswami Lab)
M.L. Sol (Student TU Delft)
Sasa Gazibegovic (Eindhoven University of Technology)
R.L.M. Op het Veld (Eindhoven University of Technology)
Stijn C. Balk (TU Delft - QRD/Kouwenhoven Lab)
Diana Car (Eindhoven University of Technology)
Erik P.A.M. Bakkers (Eindhoven University of Technology)
L.P. Kouwenhoven (TU Delft - QN/Kouwenhoven Lab)
Jie Shen (TU Delft - QRD/Kouwenhoven Lab)
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Abstract
We study superconducting quantum interference in InSb flake Josephson junctions. An even-odd effect in the amplitude and periodicity of the superconducting quantum interference pattern is found. Interestingly, the occurrence of this pattern coincides with enhanced conduction at both edges of the flake, as is deduced from measuring a superconducting quantum interference device (SQUID) pattern at reduced gate voltages. We identify the specific crystal facet of the edge with enhanced conduction, and confirm this by measuring multiple devices. Furthermore, we argue the even-odd effect is due to crossed Andreev reflection, a process where a Cooper pair splits up over the two edges and recombines at the opposite contact. An entirely h/e periodic SQUID pattern, as well as the observation of both even-odd and odd-even effects, corroborates this conclusion. Crossed Andreev reflection could be harnessed for creating a topological state of matter or performing experiments on the nonlocal spin entanglement of spatially separated Cooper pairs.
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