Qubit Zoo

Coherent Josephson Qubit Suitable for Scalable Quantum Integrated Circuits

1 min read

Introduces the Xmon: a planar transmon variant with a cross-shaped capacitor geometry enabling scalable 2D arrays with individual qubit addressability and nearest-neighbor coupling. The Xmon design became the foundation for Google’s Sycamore processor and the quantum supremacy experiment.

Key Results

  • T₁ > 40 μs, T₂* > 20 μs
  • Cross-shaped capacitor with 4 coupling ports
  • Scalable 2D tiling with individual XY and Z control
  • Single-qubit gate fidelity >99.9%, two-qubit CZ >99.4%

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