Parity Cross-Resonance: A Multiqubit Gate

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.

19 pages, 10 figures

References in corpus (40)

• Observation of many-body localization of interacting fermions in a quasi-random optical lattice
• Local conservation laws and the structure of the many-body localized states
• Parallel implementation of high-fidelity multi-qubit gates with neutral atoms
• Non-locality and Communication Complexity
• Schrieffer-Wolff transformation for quantum many-body systems
• High-fidelity parallel entangling gates on a neutral atom quantum computer
• Procedure for systematically tuning up crosstalk in the cross resonance gate
• A simple all-microwave entangling gate for fixed-frequency superconducting qubits
• Chopped random-basis quantum optimization
• Complete universal quantum gate set approaching fault-tolerant thresholds with superconducting qubits
• Realization of high-fidelity CZ and ZZ-free iSWAP gates with a tunable coupler
• Efficient many-party controlled teleportation of multi-qubit quantum information via entanglement
• Process verification of two-qubit quantum gates by randomized benchmarking
• Effective Hamiltonian models of the cross-resonance gate
• Gradient optimization of analytic controls: the route to high accuracy quantum optimal control
• Demonstration of a High-Fidelity CNOT for Fixed-Frequency Transmons with Engineered ZZ Suppression
• High fidelity two-qubit gates on fluxoniums using a tunable coupler
• Optimal control methods for fast time-varying Hamiltonians
• Suppression of Unwanted $ZZ$ Interactions in a Hybrid Two-Qubit System
• Multi-qubit gates and Schrödinger cat states in an optical clock
• Efficient Arbitrary Simultaneously Entangling Gates on a trapped-ion quantum computer
• High-fidelity three-qubit iToffoli gate for fixed-frequency superconducting qubits
• Fast multi-qubit gates by adiabatic evolution in interacting excited state manifolds
• High-contrast ZZ interaction using superconducting qubits with opposite-sign anharmonicity
• Transmon platform for quantum computing challenged by chaotic fluctuations
• Fast multi-qubit gates through simultaneous two-qubit gates
• Scalable Method for Eliminating Residual $ZZ$ Interaction between Superconducting Qubits
• Extensive characterization of a family of efficient three-qubit gates at the coherence limit
• Dual-Species, Multi-Qubit Logic Primitives for Ca+/Sr+ Trapped-Ion Crystals
• Demonstration of tunable three-body interactions between superconducting qubits
• Integrated ${}^9$Be${}^{+}$ multi-qubit gate device for the ion-trap quantum computer
• ZZ freedom in two qubit gates
• Superconducting qubits beyond the dispersive regime
• Exact quantization of superconducting circuits
• An error-protected cross-resonance switch in weakly-tuneable architectures
• Single-step high-fidelity three-qubit gates by anisotropic chiral interactions
• Entangling interactions between artificial atoms mediated by a multimode left-handed superconducting ring resonator
• Lattice Hamiltonians and Stray Interactions Within Quantum Processors
• Fault-Tolerant Stabilizer Measurements in Surface Codes with Three-Qubit Gates
• Error mitigation of entangled states using brainbox quantum autoencoders