Title: Extending the coherence time of spin defects in hBN enables advanced qubit control and quantum sensing Show Chinese title

Title: 延长hBN中自旋缺陷的相干时间可实现先进的量子比特控制和量子传感

Abstract: Spin defects in hexagonal Boron Nitride (hBN) attract increasing interest for quantum technology since they represent optically-addressable qubits in a van der Waals material. In particular, negatively-charged boron vacancy centers (${V_B}^-$) in hBN have shown promise as sensors of temperature, pressure, and static magnetic fields. However, the short spin coherence time of this defect currently limits its scope for quantum technology. Here, we apply dynamical decoupling techniques to suppress magnetic noise and extend the spin coherence time by nearly two orders of magnitude, approaching the fundamental $T_1$ relaxation limit. Based on this improvement, we demonstrate advanced spin control and a set of quantum sensing protocols to detect electromagnetic signals in the MHz range with sub-Hz resolution. This work lays the foundation for nanoscale sensing using spin defects in an exfoliable material and opens a promising path to quantum sensors and quantum networks integrated into ultra-thin structures. Show Chinese abstract

Abstract: 自旋缺陷在六方氮化硼(hBN)中由于它们代表了范德华材料中的光学可寻址量子比特，因此在量子技术中引起了越来越多的关注。特别是，hBN中的负电荷硼空位中心(${V_B}^-$)显示出作为温度、压力和静态磁场传感器的潜力。然而，这种缺陷的短自旋相干时间目前限制了其在量子技术中的应用。在这里，我们应用动态解耦技术来抑制磁噪声，并将自旋相干时间延长近两个数量级，接近基本的$T_1$退相干极限。基于这一改进，我们展示了先进的自旋控制和一组量子传感协议，以亚赫兹分辨率检测兆赫兹范围内的电磁信号。这项工作为使用可剥离材料中的自旋缺陷进行纳米尺度传感奠定了基础，并为集成到超薄结构中的量子传感器和量子网络开辟了一条有前景的路径。