Ballistic superconductivity and tunable \u03c0\u2013junctions in InSb quantum wells

Chung Ting Ke,Ray Kallaher,Tiantian Wang,Charles R Guinn,Mario Lodari,Rosa E Diaz,Sara Metti,Candice Thomas,Michael J Manfra,Srijit Goswami,Giordano Scappucci,Christian M Moehle,Folkert K De Vries,Geoffrey C Gardner

doi:10.1038/s41467-019-11742-4

Chung Ting Ke, Ray Kallaher + Show 12 more

Open Access

https://doi.org/10.1038/s41467-019-11742-4

Copy DOI

Abstract

Planar Josephson junctions (JJs) made in semiconductor quantum wells with large spin-orbit coupling are capable of hosting topological superconductivity. Indium antimonide (InSb) two-dimensional electron gases (2DEGs) are particularly suited for this due to their large Landé g-factor and high carrier mobility, however superconducting hybrids in these 2DEGs remain unexplored. Here we create JJs in high quality InSb 2DEGs and provide evidence of ballistic superconductivity over micron-scale lengths. A Zeeman field produces distinct revivals of the supercurrent in the junction, associated with a 0−π transition. We show that these transitions can be controlled by device design, and tuned in-situ using gates. A comparison between experiments and the theory of ballistic π-Josephson junctions gives excellent quantitative agreement. Our results therefore establish InSb quantum wells as a promising new material platform to study the interplay between superconductivity, spin-orbit interaction and magnetism.

Highlights

Planar Josephson junctions (JJs) made in semiconductor quantum wells with large spin-orbit coupling are capable of hosting topological superconductivity
These include the study of novel Josephson effects[1], superconducting correlations in quantum Hall systems[2,3,4,5,6,7], hybrid superconducting qubits[8,9], and emergent topological states in semiconductors with strong spinorbit interaction (SOI)[10,11,12,13]
The JJs are fabricated in an InSb 2DEG wafer grown by molecular beam epitaxy, with a nominal electron density n = 2.7 × 1011 cm−2 and mobility μ ≈ 150,000 cm2V−1s−1, which corresponds to a mean free path le ≈ 1.3 μm

Summary

Introduction

Planar Josephson junctions (JJs) made in semiconductor quantum wells with large spin-orbit coupling are capable of hosting topological superconductivity. Topological superconductivity in such 2DEGs can be realized using planar Josephson junctions (JJs), where the combined effect of SOI and a Zeeman field is known to significantly alter the current-phase relation[14,15,16].

Results

Conclusion