Complete universal quantum gate set approaching fault-tolerant thresholds with superconducting qubits

TL;DR

This paper demonstrates a complete set of high-fidelity quantum gates on superconducting qubits, approaching fault-tolerance thresholds, using quantum process tomography to characterize their performance.

Contribution

It introduces a full universal gate set with fidelities exceeding 95%, including a novel process map representation, advancing superconducting qubit scalability for error correction.

Findings

Gate fidelities exceed 95%, with some reaching 98%.

All gates characterized using quantum process tomography.

Introduces an efficient process map in the Pauli basis.

Abstract

We use quantum process tomography to characterize a full universal set of all-microwave gates on two superconducting single-frequency single-junction transmon qubits. All extracted gate fidelities, including those for Clifford group generators, single-qubit pi/4 and pi/8 rotations, and a two-qubit controlled-NOT, exceed 95% (98%), without (with) accounting for state preparation and measurement errors. Furthermore, we introduce a process map representation in the Pauli basis which is visually efficient and informative. This high-fidelity gate set serves as another critical building block towards scalable architectures of superconducting qubits for error correction schemes.