A strategy for realizing van der Waals Josephson junction arrays

Area of Science:

• Quantum Technology
• Materials Science
• Condensed Matter Physics

Background:

• Josephson junctions are fundamental to quantum technologies like superconducting qubits and voltage standards.
• Superconducting van der Waals (vW) materials offer a promising platform for quantum circuits, but face challenges in scalability and uniformity.
• Current fabrication methods for vW Josephson junctions involve sequential stacking, limiting array creation.

Purpose of the Study:

• To develop a scalable method for fabricating arrays of Josephson junctions from single van der Waals flakes.
• To demonstrate the feasibility of creating multiple Josephson junctions on the same parent flake.
• To investigate the supercurrent rectification properties of these fabricated junctions.

Main Methods:

• Utilized micromechanical stacking, lithographic patterning, and etching techniques.
• Fabricated devices with two series-connected NbSe2-NbSe2 vW Josephson junctions from a single parent flake.
• Performed low-temperature electrical transport measurements down to 1.5 K and time-domain measurements.

Main Results:

• Successfully realized devices with multiple NbSe2-NbSe2 vW Josephson junctions.
• Observed robust supercurrent rectification under in-plane magnetic fields up to 4 T.
• Confirmed the presence of magneto-chiral anisotropy, essential for rectification, and its absence under out-of-plane fields.

Conclusions:

• The proposed method enables the fabrication of Josephson junction arrays with controlled thickness and twist angle from single vW flakes.
• This approach overcomes limitations of sequential stacking and offers a scalable pathway for vW quantum circuits.
• The observed supercurrent rectification highlights the potential of this platform for novel quantum electronic devices.