Year: 2024
Type: article
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-B\"uttiker formalism, generalized to allow for Andreev reflection processes. We show that by varying the voltage of the QPC, ${V}_{\mathrm{QPC}}$, the average Andreev reflection, $A$, at the QH-SC interface can be tuned from 50% to $\ensuremath{\sim}10%$. The evolution of $A$ with ${V}_{\mathrm{QPC}}$ extracted from the measurements exhibits plateaus separated by regions for which $A$ varies continuously with ${V}_{\mathrm{QPC}}$. The presence of plateaus suggests that for some ranges of ${V}_{\mathrm{QPC}}$ the QPC might be pinching off almost completely from the QH-SC interface some of the edge modes. Our work shows an experimental setup to control and advance the understanding of the complex interplay between superconductivity and QH effect in two-dimensional gas systems.
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G11630931, G1859920734, G1871477277, G2214935549, G3398237449, G413247060, NOVEL TOPOLOGICAL JOSEPHSON JUNCTIONS ARCHITECTURES FOR FAULT-TOLERANT QUBITS AND ADVANCED SENSING, G4689434848, G4771968897, G4903105778, G5085225751, G5261598906, G5339743583, G6338696783, G6526374922, Kavli Institute for Theoretical Physics, G70797072, Kavli Institute for Theoretical Physics, G855168022, G985207216
OpenAlex ID: W4391220193