Andreev reflection of quantum Hall states through a quantum point contact

Abstract

We investigate the interplay between the quantum Hall (QH) effect and superconductivity in InAs surface quantum well (SQW)/NbTiN heterostructures using a quantum point contact (QPC). We use QPC to control the proximity of the edge states to the superconductor. By measuring the upstream and downstream resistances of the device, we investigate the efficiency of Andreev conversion at the InAs/NbTiN interface. Our experimental data is analyzed using the Landauer-Buttiker formalism, generalized to allow for Andreev reflection processes. We show that by varying the voltage of the QPC, $V_{QPC}$, the average Andreev reflection, $A$, at the QH-SC interface can be tuned from 50% to 10%. The evolution of $A$ with $V_{QPC}$ extracted from the measurements exhibits plateaus separated by regions for which $A$ varies continuously with $V_{QPC}$. The presence of plateaus suggests that for some ranges of $V_{QPC}$ the QPC might be pinching off almost completely from the QH-SC interface some of the edge modes. Our work shows a new experimental setup to control and advance the understanding of the complex interplay between superconductivity and QH effect in two-dimensional electron gas systems.

References in corpus (17)

• Non-Abelian Anyons and Topological Quantum Computation
• Exotic non-Abelian anyons from conventional fractional quantum Hall states
• InAs-Al Hybrid Devices Passing the Topological Gap Protocol
• Spin-triplet supercurrent carried by quantum Hall edge states through a Josephson junction
• Experimental probe of topological orders and edge excitations in the second Landau level
• Andreev reflection in the fractional quantum Hall state
• The relaxation time of a chiral quantum R-L circuit
• Induced superconducting pairing in integer quantum Hall edge states
• Evidence for chiral supercurrent in quantum Hall Josephson junctions
• Mechanisms of Andreev reflection in quantum Hall graphene
• Superconductivity and fermionic dissipation in quantum Hall edges
• Disorder in Andreev reflection of a quantum Hall edge
• Supercurrent-enabled Andreev reflection in a chiral quantum Hall edge state
• Loss and decoherence at the quantum Hall - superconductor interface
• Vortex-enabled Andreev processes in quantum Hall-superconductor hybrids
• Two-particle time-domain interferometry in the Fractional Quantum Hall Effect regime
• Geometrical effects on the downstream conductance in quantum-Hall--superconductor hybrid systems

Cited by in corpus (8)

• Non-local transport measurements in hybrid quantum Hall - superconducting devices
• Heat-charge separation in a hybrid superconducting quantum Hall setup
• Andreev Reflection in the Quantum Hall Regime at an Al/InAs Junction on a Cleaved Edge
• Transparent Graphene-Superconductor Interfaces: Quantum Hall and Zero Field Regimes
• Engineering superconducting contacts transparent to a bipolar graphene
• Quasi-${\Phi }_0$-periodic supercurrent at quantum Hall transitions
• Buried Dirac points in quantum spin Hall insulators: Implications for Majorana Kramers pair-based quantum computing
• Vortex Pinning in Niobium covered by a thin polycrystalline Gold