Two-Dimensional Material Tunnel Barrier for Josephson Junctions and Superconducting Qubits.

Area of Science:

• Quantum Computing
• Materials Science
• Condensed Matter Physics

Background:

• Superconducting qubits are crucial for quantum computing, relying on Josephson junctions.
• Current Josephson junctions primarily use aluminum oxide (AlO) tunnel barriers.
• Exploring alternative materials is key to advancing qubit performance and functionality.

Purpose of the Study:

• To demonstrate Josephson junctions and superconducting qubits utilizing two-dimensional (2D) materials as tunnel barriers.
• To investigate the use of molybdenum disulfide (MoS₂) for large-scale batch-fabricated Josephson junctions.
• To engineer and characterize MoS₂-based transmon qubits.

Main Methods:

• Batch fabrication of Josephson junctions using layer-by-layer stacking of N layers of MoS₂.
• Design and control of critical Josephson current in 2D material junctions.
• Engineering and characterization of MoS₂ transmon qubits within a superconducting microwave resonator.

Main Results:

• Successful demonstration of Josephson junctions with 2D materials (MoS₂) as tunnel barriers.
• Fabrication of MoS₂ transmon qubits, characterized for the first time.
• Established a method for designing critical Josephson current via controlled stacking of MoS₂ layers.

Conclusions:

• Two-dimensional materials offer a versatile platform for Josephson junctions, expanding beyond AlO.
• This approach enables access to diverse electrical and magnetic properties of 2D materials for qubit engineering.
• The findings pave the way for novel quantum circuit elements and deeper studies of material effects in superconducting qubits.