Fast, tunable, high fidelity cZ-gates between superconducting qubits with parametric microwave control of ZZ-coupling

• URL: http://arxiv.org/abs/2305.02907v3
• Date: Fri, 04 Oct 2024 18:40:45 GMT
• Title: Fast, tunable, high fidelity cZ-gates between superconducting qubits with parametric microwave control of ZZ-coupling
• Authors: X. Y. Jin, K. Cicak, Z. Parrott, S. Kotler, F. Lecocq, J. Teufel, J. Aumentado, E. Kapit, R. W. Simmonds,
• Abstract summary: We present a highly flexible parametric coupling scheme with superconducting qubits. Our fully integrated, 2D on-chip coupler design is only weakly flux tunable. benchmarking reveals that the parametric SWAP c$Z$ gate achieves an average fidelity of $99.44pm 0.09$% in a gate duration of 70ns.
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• Abstract: Future quantum information processors require tunable coupling architectures that can produce high fidelity logical gates between two or more qubits. Parametric coupling is a powerful technique for generating tunable interactions between many qubits. Here, we present a highly flexible parametric coupling scheme with superconducting qubits that provides complete removal of residual $ZZ$ coupling and the implementation of driven SWAP or SWAP-free controlled-$Z$ (c$Z$) gates. Our fully integrated, 2D on-chip coupler design is only weakly flux tunable, cancels static linear coupling between the qubits, avoids internal coupler dynamics or excitations, and is extensible to multi-qubit circuit-QED systems. Exploring gate fidelity versus gate duration allows us to maximize two-qubit gate fidelity, while providing insights into possible error sources for these gates. Randomized benchmarking over several hours reveals that the parametric SWAP c$Z$ gate achieves an average fidelity of $99.44\pm 0.09$\% in a gate duration of 70~ns and a dispersively driven parametric SWAP-free c$Z$ gate attains an average fidelity of $99.47\pm 0.07$\% in only 30~ns. The fidelity remained above this value for over 8~hours and peaked twice with a maximum of $99.67\pm 0.14$\%. Overall, our parametric approach combines versatility, precision, speed, and high performance in one compact coupler design.

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