Residual-$ZZ$-coupling suppression and fast two-qubit gate for Kerr-cat qubits based on level-degeneracy engineering

• URL: http://arxiv.org/abs/2410.00431v1
• Date: Tue, 1 Oct 2024 06:26:07 GMT
• Title: Residual-$ZZ$-coupling suppression and fast two-qubit gate for Kerr-cat qubits based on level-degeneracy engineering
• Authors: Takaaki Aoki, Akiyoshi Tomonaga, Kosuke Mizuno, Shumpei Masuda,
• Abstract summary: Building large-scale quantum computers requires an interqubit-coupling scheme with a high on-off ratio. We propose a $ZZ$-coupling scheme for two Kerr-cat qubits with a frequency-tunable coupler.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Building large-scale quantum computers requires an interqubit-coupling scheme with a high on-off ratio to avoid unwanted crosstalk coming from residual coupling and to enable fast multi-qubit operations. We propose a $ZZ$-coupling scheme for two Kerr-cat qubits with a frequency-tunable coupler. By making four relevant states of the two Kerr-cat qubits quadruply degenerate, we can switch off the $ZZ$ coupling. By partially lifting the level degeneracy, we can switch it on. We theoretically show that an experimentally feasible circuit model suppresses the residual $ZZ$ coupling. Moreover, our circuit can realize $R_{ZZ}(-\pi/2)$-gate fidelity higher than $99.999\%$ within $25\,$ns when decoherence is ignored.

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