# Demonstration of Universal Parametric Entangling Gates on a Multi-Qubit Lattice

## TL;DR

This paper demonstrates a universal set of entangling gates on a multi-qubit superconducting processor using parametric coupling, achieving high fidelity and scalability potential.

## Contribution

It introduces a method for implementing selective, high-fidelity entangling gates on multi-qubit arrays via frequency modulation techniques.

## Key findings

- Achieved an average process fidelity of 93% for three two-qubit gates.
- Prepared a four-qubit maximally entangled state demonstrating gate performance.
- Observed an average fidelity of 91.6% across various two-qubit permutations.

## Abstract

We show that parametric coupling techniques can be used to generate selective entangling interactions for multi-qubit processors. By inducing coherent population exchange between adjacent qubits under frequency modulation, we implement a universal gateset for a linear array of four superconducting qubits. An average process fidelity of $\mathcal{F}=93\%$ is estimated for three two-qubit gates via quantum process tomography. We establish the suitability of these techniques for computation by preparing a four-qubit maximally entangled state and comparing the estimated state fidelity against the expected performance of the individual entangling gates. In addition, we prepare an eight-qubit register in all possible bitstring permutations and monitor the fidelity of a two-qubit gate across one pair of these qubits. Across all such permutations, an average fidelity of $\mathcal{F}=91.6\pm2.6\%$ is observed. These results thus offer a path to a scalable architecture with high selectivity and low crosstalk.