Sapphire (Al₂O₃) Substrate

Superconducting Materials

Ultra-Low-Loss Substrate for High-Coherence Qubits

Non-superconducting — crystalline dielectric

Sapphire (Al₂O₃) Substrate

Ultra-Low-Loss Substrate for High-Coherence Qubits

Role in quantum circuits

Low-loss substrate for high-coherence qubit circuits; alternative to silicon

Why it matters

Sapphire offers extremely low dielectric loss and a very clean surface, resulting in

longer qubit coherence times ((T_1), T2). It is useful in processor designs where maximising coherence is critical.

Key facts

  • Dielectric constant ~9–10; very low loss tangent

  • Single-crystal c-plane (0001) orientation preferred

  • Cleaner surfaces reduce two-level system (TLS) defects

  • Well suited for high-coherence qubit layouts

  • Higher cost than silicon but delivers superior coherence times