Enabling full localization of qubits and gates with a multi-mode coupler

• URL: http://arxiv.org/abs/2509.26211v1
• Date: Tue, 30 Sep 2025 13:13:47 GMT
• Title: Enabling full localization of qubits and gates with a multi-mode coupler
• Authors: Zhongyi Jiang, Simon Geisert, Sören Ihssen, Ioan M. Pop, Mohammad H. Ansari,
• Abstract summary: Tunable couplers are a key building block of superconducting quantum processors.<n>We propose a multi-mode tunable coupler that enables nonlinear control of interactions across excitation manifold.<n>The proposed design also realizes complete localization between qubits, providing perfect isolation at the decoupled point.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Tunable couplers are a key building block of superconducting quantum processors, enabling high on-off ratios for two-qubit entangling interactions. While crosstalk can be mitigated in idle mode, conventional single-mode couplers lack independent control over interactions in the one- and two-excitation manifolds, leading to unitary errors such as leakage during gate operations. Moreover, even at the nominal decoupled point, residual wavefunction delocalization persists, causing unintended qubit-qubit coupling. Here we propose a multi-mode tunable coupler that enables nonlinear control of interactions across excitation manifolds, achieving a high on-off ratio in the one-excitation manifold while suppressing coupling in the two-excitation manifold. The proposed design also realizes complete localization between qubits, providing perfect isolation at the decoupled point and opening new possibilities for scalable, high-fidelity quantum gates.

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