Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science. 2022 Mar 4;375(6584):1017-1020. doi: 10.1126/science.abe6437. Epub 2022 Mar 3.
Magnetic monopoles play a central role in areas of physics that range from electromagnetism to topological matter. String theory promotes conventional vector gauge fields of electrodynamics to tensor gauge fields and predicts the existence of more exotic tensor monopoles. Here, we report the synthesis of a tensor monopole in a four-dimensional parameter space defined by the spin degrees of freedom of a single solid-state defect in diamond. Using two complementary methods, we characterized the tensor monopole by measuring its quantized topological charge and its emanating Kalb-Ramond field. By introducing a fictitious external field that breaks chiral symmetry, we further observed an intriguing spectral transition, characterized by spectral rings protected by mirror symmetries. Our work demonstrates the possibility of emulating exotic topological structures inspired by string theory.
磁单极子在物理学的多个领域中起着核心作用，这些领域包括电磁学和拓扑物质。弦论将电磁学的传统矢量规范场推广到张量规范场，并预言了更奇异的张量磁单极子的存在。在这里，我们报告了在由金刚石中单个固态缺陷的自旋自由度定义的四维参数空间中合成张量磁单极子。使用两种互补的方法，我们通过测量其量子化拓扑电荷和发出的 Kalb-Ramond 场来表征张量磁单极子。通过引入破坏手征对称性的虚拟外部场，我们进一步观察到一个有趣的谱跃迁，其特征是由镜像对称性保护的谱环。我们的工作证明了模拟受弦论启发的奇异拓扑结构的可能性。
