Realization of fast all-microwave CZ gates with a tunable coupler

TL;DR

This paper demonstrates a fast, high-fidelity all-microwave controlled-Z gate in superconducting qubits using tunable couplers, achieving 99.38% fidelity in 100 ns without pulse correction.

Contribution

It introduces a novel all-microwave CZ gate with tunable couplers that is robust against pulse distortion and suitable for scalable quantum hardware.

Findings

Achieved a 100 ns CZ gate with 99.38% fidelity.

The gate is unaffected by pulse distortion and does not require pulse correction.

Provides a blueprint for high-integrability quantum hardware design.

Abstract

The development of high-fidelity two-qubit quantum gates is essential for digital quantum computing. Here, we propose and realize an all-microwave parametric Controlled-Z (CZ) gates by coupling strength modulation in a superconducting Transmon qubit system with tunable couplers. After optimizing the design of the tunable coupler together with the control pulse numerically, we experimentally realized a 100 ns CZ gate with high fidelity of 99.38%$ \pm$0.34% and the control error being 0.1%. We note that our CZ gates are not affected by pulse distortion and do not need pulse correction, {providing a solution for the real-time pulse generation in a dynamic quantum feedback circuit}. With the expectation of utilizing our all-microwave control scheme to reduce the number of control lines through frequency multiplexing in the future, our scheme draws a blueprint for the high-integrable quantum hardware design.