An argon ion beam milling process for native ${\text{AlO}}_{\text{x}}$ layers enabling coherent superconducting contacts

Abstract

We present an argon ion beam milling process to remove the native oxide layer forming on aluminum thin films due to their exposure to atmosphere in between lithographic steps. Our cleaning process is readily integrable with conventional fabrication of Josephson junction quantum circuits. From measurements of the internal quality factors of superconducting microwave resonators with and without contacts, we place an upper bound on the residual resistance of an ion beam milled contact of 50$\mathrm{m}\Omega \cdot \mu {\mathrm{m}}^2$ at a frequency of 4.5 GHz. Resonators for which only $6\%$ of the total foot-print was exposed to the ion beam milling, in areas of low electric and high magnetic field, showed quality factors above $10^6$ in the single photon regime, and no degradation compared to single layer samples. We believe these results will enable the development of increasingly complex superconducting circuits for quantum information processing.

4 pages, 4 figures, supplementary material

References in corpus (10)

• Coupling Superconducting Qubits via a Cavity Bus
• Superconducting qubit in waveguide cavity with coherence time approaching 0.1ms
• Observation of quantum jumps in a superconducting artificial atom
• A widely tunable parametric amplifier based on a SQUID array resonator
• Efficient and robust analysis of complex scattering data under noise in microwave resonators
• Detecting bit-flip errors in a logical qubit using stabilizer measurements
• Microwave Dielectric Loss at Single Photon Energies and milliKelvin Temperatures
• Demonstrating a Driven Reset Protocol of a Superconducting Qubit
• Characterization and Reduction of Capacitive Loss Induced by Sub-Micron Josephson Junction Fabrication in Superconducting Qubits
• Overlap junctions for high coherence superconducting qubits

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