近日，广西大学张程贤团队研究了硅基双量子点中的几何双量子比特门。2025年4月10日出版的《物理评论A》杂志发表了这项成果。

实现高保真双量子比特门对于硅基双量子点中的自旋量子比特至关重要。然而，在实验环境中，这些门对电荷噪声很敏感，这仍然是一个重大挑战。几何门利用纯几何相位进行门操作，是实现鲁棒控制的一种有前景的方法。在这项工作中，研究组从理论上提出了一种可行的策略，在考虑实验控制环境的情况下，为硅基自旋量子比特实现几何双量子比特门。

通过在局部磁场梯度明显大于交换相互作用的适当区域操作，研究组可以通过分析和数值方法实现纠缠和非纠缠几何门。研究发现，所获得的几何栅极与硅中使用电偶极自旋共振的现有实验技术高度兼容。此外，所实现的几何控制-??（CZ）门在实验噪声水平下可以实现超过99%的保真度，门时间短至20ns。该工作为在硅中实现自旋量子比特的高保真几何双量子比特门铺平了道路。

附：英文原文

Title: Geometric two-qubit gates in silicon-based double quantum dots

Author: Yong-Yang Lu, Kejin Wei, Chengxian Zhang

Issue&Volume: 2025/04/10

Abstract: Achieving high-fidelity two-qubit gates is crucial for spin qubits in silicon-based double quantum dots. However, these gates are sensitive to charge noise in experimental settings, which remains a significant challenge. Geometric gates, which utilize pure geometric phases for gate operations, are a promising approach to achieving robust control. In this work, we theoretically propose a feasible strategy to implement geometric two-qubit gates for silicon-based spin qubits considering experimental control environments. By operating in the suitable region where the local magnetic field gradient is significantly larger than the exchange interaction, we can implement both entangling and nonentangling geometric gates through analytical and numerical methods. It is found that the geometric gates obtained are highly compatible with existing experimental techniques using electric dipole spin resonance in silicon. Moreover, the implemented geometric controlled-Z (CZ) gates can achieve fidelities exceeding 99% under experimental noise levels and the gate times are as short as 20 ns. Our work paves the way for the realization of high-fidelity geometric two-qubit gates for spin qubits in silicon.

DOI: 10.1103/PhysRevA.111.042609

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.042609