# Parity Cross-Resonance: A Multiqubit Gate

arXiv: https://arxiv.org/abs/2508.10807 · HTML: https://mlsanity.com/paper/2508.10807/

## Key facts

- No citing papers in the map yet (data through 14 Oct 2026).
- Builds on 3 of its 82 references that are in the map.
- First posted on arXiv 14 Aug 2025.

## Builds on (most cited first, 3 of 3)

- [Learning to Decode the Surface Code with a Recurrent, Transformer-Based Neural Network](https://mlsanity.com/paper/2310.05900/) (2023)
- [How to Build a Quantum Supercomputer: Scaling from Hundreds to Millions of Qubits](https://mlsanity.com/paper/2411.10406/) (2024)
- [Exploring Quantum Control Landscape and Solution Space Complexity through Dimensionality Reduction & Optimization Algorithms](https://mlsanity.com/paper/2502.11905/) (2025)

## Abstract (arXiv)

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.