A double-resonator coupler for high-fidelity two-qubit gates between superconducting qubits
Abstract
Tunable couplers have enabled two-qubit gate fidelities in superconducting quantum processors to approach 99.9%, yet simultaneously suppressing residual interactions and maintaining flexible qubit-frequency allocation remain central challenges for scaling. Here, we propose a double-resonator coupler (DRC) consisting of two resonators interconnected by a single Josephson junction and a capacitor. The hybridized resonator modes provide two mediated exchange paths whose interference controls the qubit-qubit interaction. The DRC enables complete cancellation of residual ZZ interaction for qubit-qubit detunings well outside the straddling regime, even in the absence of direct qubit-qubit coupling, thereby relaxing constraints on frequency allocation and qubit placement. Away from the idle point, the same circuit provides a strong ZZ interaction of approximately 70 MHz, enabling a 20 ns controlled-Z gate with simulated coherent infidelity below 10−5. These results establish the DRC as a flexible single-junction coupler architecture for high-fidelity superconducting quantum processors.
Related
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BibTeX
@misc{jin2026doubleresonator,
title = {{A double-resonator coupler for high-fidelity two-qubit gates between superconducting qubits}},
author = {Seunghyeon Jin and Seungha Woo and Shinyoung Hwang and June-Young M. Lee and Jeongmin Shim and Sunje Kim and Dae Seok Han and Jaeho Shin and Eunjong Kim},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.05222},
eprint = {2609.05222},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.05222},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A double-resonator coupler for high-fidelity two-qubit gates between superconducting qubits
AU - Seunghyeon Jin
AU - Seungha Woo
AU - Shinyoung Hwang
AU - June-Young M. Lee
AU - Jeongmin Shim
AU - Sunje Kim
AU - Dae Seok Han
AU - Jaeho Shin
AU - Eunjong Kim
PY - 2026
DA - 2026/09/09
PB - arXiv
DO - 10.48550/arxiv.2609.05222
UR - https://arxiv.org/abs/2609.05222
AB - Tunable couplers have enabled two-qubit gate fidelities in superconducting quantum processors to approach 99.9%, yet simultaneously suppressing residual interactions and maintaining flexible qubit-frequency allocation remain central challenges for scaling. Here, we propose a double-resonator coupler (DRC) consisting of two resonators interconnected by a single Josephson junction and a capacitor. The hybridized resonator modes provide two mediated exchange paths whose interference controls the qubit-qubit interaction. The DRC enables complete cancellation of residual ZZ interaction for qubit-qubit detunings well outside the straddling regime, even in the absence of direct qubit-qubit coupling, thereby relaxing constraints on frequency allocation and qubit placement. Away from the idle point, the same circuit provides a strong ZZ interaction of approximately 70 MHz, enabling a 20 ns controlled-Z gate with simulated coherent infidelity below 10^−5. These results establish the DRC as a flexible single-junction coupler architecture for high-fidelity superconducting quantum processors.
ER -