Transport regimes of a split gate superconducting quantum point contact in the two-dimensional LaAlO3/SrTiO3 superfluid
Holger Thierschmann (QN/Klapwijk Lab)
E. Mulazimoglu (TU Delft - QN/Caviglia Lab)
N. Manca (TU Delft - QN/Caviglia Lab)
S Goswami (TU Delft - QRD/Goswami Lab, TU Delft - QuTech Advanced Research Centre)
T. M. Klapwijk (QN/Klapwijk Lab, Chemistry Faculty of M. V. Lomonosov Moscow State University)
A. D. Caviglia (TU Delft - QN/Caviglia Lab)
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Abstract
One of the hallmark experiments of quantum transport is the observation of the quantized resistance in a point contact in GaAs/AlGaAs heterostructures. Being formed with split gate technology, these structures represent in an ideal manner equilibrium reservoirs which are connected only through a few electron mode channel. It has been a long standing goal to achieve similar experimental conditions also in superconductors. Here we demonstrate the formation of a superconducting quantum point contact (SQPC) with split gate technology in a two-dimensional superconductor, utilizing the unique gate tunability of the superfluid at the LaAlO3/SrTiO3 interface. When the constriction is tuned through the action of metallic split gates we identify three regimes of transport: First, SQPC for which the supercurrent is carried only by a few quantum transport channels. Second, superconducting island strongly coupled to the equilibrium reservoirs. Third, charge island with a discrete spectrum weakly coupled to the reservoirs.
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