Qubit Zoo

Tunable Coupling Scheme for Implementing High-Fidelity Two-Qubit Gates

1 min read

Proposes and analyzes a tunable coupling scheme for superconducting qubits using a frequency-tunable transmon as a coupler element between two fixed-frequency qubits. Demonstrates that the effective qubit-qubit coupling can be tuned from positive through zero to negative, enabling high-fidelity two-qubit gates with suppressed always-on ZZ interaction.

Key Results

  • Coupling tunability: +5 MHz to −5 MHz (through zero)
  • ZZ suppression: residual ZZ < 10 kHz at the off point
  • Gate scheme: parametric modulation of coupler frequency
  • Theoretical CZ gate fidelity > 99.9% with realistic parameters
  • Foundation for Google Sycamore and IBM Eagle/Heron architectures

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