Shadow-wall lithography of ballistic superconductor-semiconductor quantum devices

Area of Science:

• Quantum Computing
• Condensed Matter Physics
• Nanotechnology

Background:

• Realizing hybrid superconductor-semiconductor quantum devices, including topological qubits, requires advanced fabrication techniques.
• Existing methods often struggle with reproducibility and preserving the integrity of delicate hybrid interfaces.

Purpose of the Study:

• To introduce a novel on-chip fabrication paradigm using shadow walls.
• To improve the quality and reproducibility of superconductor-semiconductor hybrid devices.
• To facilitate the development of topological qubits.

Main Methods:

• Implementation of an on-chip fabrication paradigm utilizing shadow walls.
• Elimination of critical fabrication steps like lithography and etching to preserve interface homogeneity.
• Fabrication of nanowire Josephson junctions and 3-terminal devices.

Main Results:

• Achieved substantial advances in device quality and reproducibility.
• Demonstrated devices with a hard induced superconducting gap and ballistic normal-/superconductor junctions.
• Observed large gate-tunable supercurrents and high-order multiple Andreev reflections, indicating exceptional coherence.
• Observed concurrent emergence of zero-bias conductance peaks at both boundaries of 1D hybrids in a magnetic field.

Conclusions:

• The shadow wall fabrication approach simplifies the reproducible creation of high-quality hybrid quantum devices.
• This method is critical for preserving fragile hybrid interfaces, enabling robust topological qubit realization.
• The demonstrated device coherence and properties pave the way for advanced quantum information processing.