Preprint FZJ-2025-04656

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Parity Cross-Resonance: A Multiqubit Gate

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2025

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Report No.: arXiv:2508.10807

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.


Note: 19 pages, 10 figures

Contributing Institute(s):
  1. Theoretische Nanoelektronik (PGI-2)
Research Program(s):
  1. 5221 - Advanced Solid-State Qubits and Qubit Systems (POF4-522) (POF4-522)

Appears in the scientific report 2025
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 Record created 2025-11-25, last modified 2025-11-25


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