Aluminum (Al)

Superconducting Materials

The Workhorse of Superconducting Qubits

Tc = 1.2 K

Aluminum (Al)

The Workhorse of Superconducting Qubits

Role in quantum circuits

Qubit body, Josephson junction electrodes, resonators, coplanar waveguides

Why it matters

Aluminum’s native oxide (AlOx) forms a reproducible ~1–2 nm tunnel barrier for Josephson

junctions — the heart of every superconducting qubit. Its long coherence times and CMOS-compatible deposition make it one of the most practical materials for scalable superconducting qubit fabrication.

Key facts

  • Type I superconductor — minimal trapped flux vortices

  • Naturally forms AlOx tunnel barrier (~1–2 nm thick)

  • Shadow evaporation enables precise Josephson junction fabrication

  • Compatible with scalable superconducting qubit fabrication workflows

  • Low decoherence from TLS defects when surface is clean