New material platform for superconducting transmon qubits with coherence times exceeding 0.3 milliseconds

Area of Science:

• Quantum computing
• Quantum science
• Superconducting circuits

Background:

• Superconducting transmon qubits are key for quantum technologies.
• Current qubit lifetimes are limited by surface effects, not bulk material properties.
• Previous attempts to improve lifetimes by minimizing surface contributions have yielded limited success.

Purpose of the Study:

• To enhance the coherence and relaxation times of two-dimensional transmon qubits.
• To identify material-level improvements for overcoming limitations in qubit performance.
• To enable higher gate fidelities in multi-qubit quantum processors.

Main Methods:

• Fabrication of two-dimensional transmon qubits using tantalum instead of niobium.
• Characterization of qubit lifetimes and coherence times.
• Utilizing dynamical decoupling techniques to assess qubit stability.

Main Results:

• Achieved qubit lifetimes and coherence times exceeding 0.3 milliseconds.
• Observed robust improvements across seventeen independently fabricated devices.
• Demonstrated the efficacy of tantalum as a superior material for transmon qubit fabrication.

Conclusions:

• Replacing niobium with tantalum in transmon qubits significantly improves qubit performance.
• Material innovation is a viable path to overcome surface-limited decoherence.
• These findings pave the way for more robust and scalable quantum processors.