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Cancellation of unwanted ZZ interactions for cross-resonance gates by superconducting qubit engineering

Roni Winik, Catherine Leroux, Agustín Di Paolo +16 more

Bulletin of the American Physical SocietyMar 17, 20210 citations

Controlling superconducting qubits in the presence of a strong, constant ZZ interaction

Seth Merkel

Bulletin of the American Physical SocietyFeb 29, 20120 citations

Scalable Method for Eliminating Residual ZZ Interaction between Superconducting Qubits

Zhongchu Ni, Sai Li, Libo Zhang +11 more

Unwanted ZZ interaction is a quantum-mechanical crosstalk phenomenon which correlates qubit dynamics and is ubiquitous in superconducting qubit systems. It adversely affects the quality of quantum operations and can be detrimental in scalable quantum information processing. Here we propose and experimentally demonstrate a practically extensible approach for complete cancellation of residual ZZ interaction between fixed-frequency transmon qubits, which are known for long coherence and simple control. We apply to the intermediate coupler that connects the qubits a weak microwave drive at a properly chosen frequency in order to noninvasively induce an ac Stark shift for ZZ cancellation. We verify the cancellation performance by measuring vanishing two-qubit entangling phases and ZZ correlations. In addition, we implement a randomized benchmarking experiment to extract the idling gate fidelity which shows good agreement with the coherence limit, demonstrating the effectiveness of ZZ cancellation. Our method allows independent addressability of each qubit-qubit connection and is applicable to both nontunable and tunable couplers, promising better compatibility with future large-scale quantum processors.Unwanted ZZ interaction is a quantum-mechanical crosstalk phenomenon which correlates qubit dynamics and is ubiquitous in superconducting qubit systems. It adversely affects the quality of quantum operations and can be detrimental in scalable quantum information processing. Here we propose and experimentally demonstrate a practically extensible approach for complete cancellation of residual ZZ interaction between fixed-frequency transmon qubits, which are known for long coherence and simple control. We apply to the intermediate coupler that connects the qubits a weak microwave drive at a properly chosen frequency in order to noninvasively induce an ac Stark shift for ZZ cancellation. We verify the cancellation performance by measuring vanishing two-qubit entangling phases and ZZ correlations. In addition, we implement a randomized benchmarking experiment to extract the idling gate fidelity which shows good agreement with the coherence limit, demonstrating the effectiveness of ZZ cancellation. Our method allows independent addressability of each qubit-qubit connection and is applicable to both nontunable and tunable couplers, promising better compatibility with future large-scale quantum processors.

arXiv:2111.13292Physical Review LettersJul 22, 202248 citations

Engineering Robust Superconducting Qubits

Nate Earnest, Thomas Von Yu, Yao Lu +4 more

Bulletin of the American Physical SocietyMar 3, 20140 citations

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

Jaseung Ku, Xuexin Xu, Markus Brink +4 more

Mitigating crosstalk errors, whether classical or quantum mechanical, is critically important for achieving high-fidelity entangling gates in multiqubit 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.Mitigating crosstalk errors, whether classical or quantum mechanical, is critically important for achieving high-fidelity entangling gates in multiqubit 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.

arXiv:2003.02775Physical Review LettersNov 11, 2020111 citations

Taking Control of Superconducting Qubits

Irfan A. Siddiqi

Bulletin of the American Physical SocietyMar 7, 20140 citations

Cancellation of unwanted ZZ interactions by superconducting qubit engineering

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