Superconducting quantum point contact with split gates in the two dimensional LaAlO3/SrTiO3 superfluid

Abstract

One of the hallmark experiments of quantum transport is the observation of the quantized resistance in a point contact formed with split gates in GaAs/AlGaAs heterostructures. Being carried out on a single material, they represent in an ideal manner equilibrium reservoirs which are connected only through a few electron mode channel with certain transmission coefficients. It has been a long standing goal to achieve similar experimental conditions also in superconductors, only reached in atomic scale mechanically tunable break junctions of conventional superconducting metals, but here the Fermi wavelength is so short that it leads to a mixing of quantum transport with atomic orbital physics. Here we demonstrate for the first time the formation of a superconducting quantum point contact (SQPC) with split gate technology in a superconductor, utilizing the unique gate tunability of the two dimensional superfluid at the LaAlO3/SrTiO3 (LAO/STO) interface. When the constriction is tuned through the action of metallic split gates we identify three regimes of transport: (i) SQPC for which the supercurrent is carried only by a few quantum transport channels. (ii) Superconducting island strongly coupled to the equilibrium reservoirs. (iii) Charge island with a discrete spectrum weakly coupled to the reservoirs. Our experiments demonstrate the feasibility of a new generation of mesoscopic all-superconductor quantum transport devices.

18 pages

References in corpus (9)

• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Quantum dot behavior in graphene nanoconstrictions
• Resonant tunnelling features in the transport spectroscopy of quantum dots
• Magnetic and Superconducting Ordering at LaAlO3/SrTiO3 Interfaces
• Nanoscale Electrostatic Control of Oxide Interfaces
• Side gate tunable Josephson junctions at the LaAlO${}_3$/SrTiO${}_3$ interface
• Quantum interference in an interfacial superconductor
• Micrometer-scale ballistic transport of electron pairs in LaAlO3/SrTiO3 nanowires
• Tunneling into a quantum confinement created by a single-step nano-lithography of conducting oxide interfaces

Cited by in corpus (16)

• Non-linear $IV$ characteristics in two-dimensional superconductors: Berezinskii-Kosterlitz-Thouless physics vs inhomogeneity
• Selective Control of Conductance Modes in Multi-terminal Josephson Junctions
• Levitons in superconducting point contacts
• Gate-tunable hallmarks of unconventional superconductivity in non-centrosymmetric nanowires
• Anomalous Josephson Coupling and High-Harmonics in Non-Centrosymmetric Superconductors with $S$-wave Spin-Triplet Pairing
• Analytic approach to transport in superconducting junctions with arbitrary carrier density
• Building a bigger Hilbert space for superconducting devices, one Bloch state at a time
• Bimodal Phase Diagram of the Superfluid Density in LaAlO3/SrTiO3 Revealed by an Interfacial Waveguide Resonator
• Quantized critical supercurrent in SrTiO${}_3$-based quantum point contacts
• Ballistic transport through quantum point contacts of multi-orbital oxides
• Optically induced resonant tunneling of electrons in nanostructures
• Electric dipole spin resonance in single and two electron quantum dot defined in two-dimensional electron gas at the SrTiO${}_3$/LaAlO${}_3$ interface
• Electronic transport in sub-micrometric channels at the LaAlO${}_3$/SrTiO${}_3$ interface
• Inhomogeneous superconductivity and quasilinear magnetoresistance at amorphous LaTiO3/SrTiO3 interfaces
• Particle-hole spectral asymmetry at the edge of multiorbital noncentrosymmetric superconductors
• Scanning gate microscopy probing of anisotropic electron flow in a two dimensional electron gas at the (110) ${\mathrm{LaAlO}}_3/{\mathrm{SrTiO}}_3$ interface: A theoretical investigation