Efficient Implementation of Arbitrary Two-Qubit Gates via Unified Control

TL;DR

This paper demonstrates a unified control scheme for superconducting qubits that can generate any two-qubit gate with high fidelity, simplifying control complexity and enhancing quantum device performance.

Contribution

The authors introduce a versatile, high-fidelity two-qubit gate implementation using only exchange interaction and qubit driving, achieving maximum expressivity and reduced control complexity.

Findings

Achieved average gate fidelity of 99.37% across various two-qubit unitaries.

Successfully implemented the B gate, enabling efficient synthesis of all two-qubit gates.

Demonstrated high-fidelity multipartite entangled state preparation.

Abstract

The native gate set is fundamental to the performance of quantum devices, as it governs the accuracy of basic quantum operations and dictates the complexity of implementing quantum algorithms. Traditional approaches to extending gate sets often require accessing multiple transitions within an extended Hilbert space, leading to increased control complexity while offering only a limited set of gates. Here, we experimentally demonstrate a unified and highly versatile gate scheme capable of natively generating arbitrary two-qubit gates using only exchange interaction and qubit driving on a superconducting quantum processor, achieving maximum expressivity. Using a state-of-the-art transmon-coupler-transmon architecture, we achieve high fidelities averaging $99.37 \pm 0.07\%$ across a wide range of commonly used two-qubit unitaries. This outstanding performance, combined with reduced complexity, enables precise multipartite entangled state preparation, as demonstrated. To further enhance its applicability, we also show the high-fidelity realization of the unique B gate, which efficiently synthesizes the entire family of two-qubit gates. Our results highlight that fully exploiting the capabilities of a single interaction can yield a comprehensive and highly accurate gate set. With maximum expressivity, gate-time optimality, demonstrated high fidelity, and easy adaptability to other quantum platforms, our unified control scheme paves the way for optimal performance in quantum devices, offering exciting prospects for advancing quantum hardware and algorithm development.