Sapphire (Al₂O₃) Substrate
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**Superconducting Materials**

 

Ultra-Low-Loss Substrate for High-Coherence Qubits

**Non-superconducting — crystalline dielectric**

Sapphire (Al₂O₃) Substrate
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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