Suppression of Unwanted ZZ Interactions in a Hybrid Two-Qubit System

  1. Jaseung Ku,
  2. Xuexin Xu,
  3. Markus Brink,
  4. David C. McKay,
  5. Jared B. Hertzberg,
  6. Mohammad H. Ansari,
  7. and B. L. T. Plourde
Mitigating crosstalk errors, whether classical or quantum mechanical, is critically important for achieving high-fidelity entangling gates in multi-qubit circuits. For weakly anharmonic
superconducting qubits, unwanted ZZ interactions can be suppressed by combining qubits with opposite anharmonicity. We present experimental measurements and theoretical modeling of two-qubit gate error for gates based on the cross resonance interaction between a capacitively shunted flux qubit and a transmon and demonstrate the elimination of the ZZ interaction.