Parity Cross-Resonance: A Multiqubit Gate

• URL: http://arxiv.org/abs/2508.10807v1
• Date: Thu, 14 Aug 2025 16:26:32 GMT
• Title: Parity Cross-Resonance: A Multiqubit Gate
• Authors: Xuexin Xu, Siyu Wang, Radhika Joshi, Rihan Hai, Mohammad H. Ansari,
• Abstract summary: We present a native three-qubit entangling gate that exploits engineered interactions to realize control-control-target and control-target-target operations.<n>We show it can be utilized in several ways, for example, in GHZ triplet state preparation.
• Score: 5.6995215414894735
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We present a native three-qubit entangling gate that exploits engineered interactions to realize control-control-target and control-target-target operations in a single coherent step. Unlike conventional decompositions into multiple two-qubit gates, our hybrid optimization approach selectively amplifies desired interactions while suppressing unwanted couplings, yielding robust performance across the computational subspace and beyond. The new gate can be classified as a cross-resonance gate. We show it can be utilized in several ways, for example, in GHZ triplet state preparation, Toffoli-class logic demonstrations with many-body interactions, and in implementing a controlled-ZZ gate. The latter maps the parity of two data qubits directly onto a measurement qubit, enabling faster and higher-fidelity stabilizer measurements in surface-code quantum error correction. In all these examples, we show that the three-qubit gate performance remains robust across Hilbert space sizes, as confirmed by testing under increasing total excitation numbers. This work lays the foundation for co-designing circuit architectures and control protocols that leverage native multiqubit interactions as core elements of next-generation superconducting quantum processors.

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