Global Parametric Gates for Multi-qubit Entanglement

TL;DR

This paper introduces a global parametric gate that efficiently produces multi-qubit entangled states in a single step, demonstrating high fidelities up to 4 qubits and predicting scalability to six qubits.

Contribution

The work presents a novel global parametric control scheme for multi-qubit entanglement that is reconfigurable, microwave-driven, and compatible with fixed-frequency qubits, with experimental and simulation validation.

Findings

Achieved 99.4% fidelity for two-qubit entanglement

Achieved 93.4% fidelity for three-qubit entanglement

Predicted 99.70% fidelity for six-qubit entanglement

Abstract

We propose and experimentally demonstrate a global parametric gate that generates multi-qubit entangled states in a single step. By applying a parametric drive to a common qubit at precise detunings relative to computational qubits, we directly produce two-, three-, and four-qubit entanglement with state fidelities of 99.4\%\pm0.2\%, 93.4\%\pm0.3\%, and 91.4\%\pm0.3\%, respectively. This scheme enables efficient, reconfigurable control using only microwave drives and is compatible with fixed-frequency qubits. Error analyses indicate that infidelity stems primarily from decoherence and coherent control errors, with negligible contributions from static ZZ coupling and flux noise. Furthermore, simulations with state-of-the-art parameters predict this global gate can generate high-fidelity (99.70\%) entanglement in systems of up to six qubits.