西北师范大学豆福全团队研究了用于固定耦合和固定频率传输量子比特的微波激活双量子比特门。2025年3月11日出版的《物理评论A》杂志发表了这项成果。

固定频率超导量子系统的全微波控制提供了降低控制电路复杂性和提高系统相干性的潜力。然而，由于量子位参数的控制灵活性有限，为了用不可调元素扩展量子位架构，必须解决几个问题，如量子串扰和频率拥挤。

研究组提出了一种微波激活的双量子比特门方案，用于通过固定频率传输耦合器耦合的两个固定频率传输量子比特。该协议依赖于仅向耦合器施加微波脉冲，从而实现受控z门。研究组证明，在150 ns内可以实现超过0.999的栅极保真度，不包括退相干效应。此外，该研究还表明，从计算子空间到非计算状态的泄漏也可以得到有效抑制。

附：英文原文

Title: Microwave-activated two-qubit gates for fixed-coupling and fixed-frequency transmon qubits

Author: Ling Jiang, Peng Xu, Shengjun Wu, Jian-An Sun, Fu-Quan Dou

Issue&Volume: 2025/03/11

Abstract: All-microwave control of fixed-frequency superconducting quantum systems offers the potential to reduce control circuit complexity and increase system coherence. Nevertheless, due to the limited control flexibility in qubit parameters, one has to address several issues, such as quantum crosstalk and frequency crowding, for scaling up qubit architecture with nontunable elements. This paper proposes a microwave-activated two-qubit gate scheme for two fixed-frequency transmon qubits coupled via a fixed-frequency transmon coupler. The protocol relies on applying a microwave pulse exclusively to the coupler, enabling the implementation of a controlled-Z gate. We show that the gate fidelity exceeding 0.999 can be achieved within 150 ns, excluding decoherence effects. Moreover, we also show that leakage from the computational subspace to noncomputational states can also be effectively suppressed.

DOI: 10.1103/PhysRevA.111.032609

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.032609