标题： 激发和相干控制具有亚兆赫兹光谱分辨率的自旋量子位模式 显示英文标题

标题： Excitation and coherent control of spin qudit modes with sub-MHz spectral resolution

摘要： 量子比特或量子位是两能级系统，它是量子计算、模拟、通信和传感的基础。高维量子态，即三量子比特（D = 3）和特别是多量子比特（D = 4 或更高），提供了显著的优势。特别是，它们可以提供抗噪声的量子密码学，简化量子逻辑并提高量子计量学。飞行和固态多量子比特分别基于光子芯片和超导电路实现。然而，目前仍缺乏具有长相干时间和高光谱分辨率的室温多量子比特。碳化硅（SiC）中的硅空位中心，自旋 S = 3/2，在这方面非常有前景，但到目前为止它们被当作标准量子位系统处理。在这里，我们在环境条件下应用双频协议来激发和成像 SiC 自旋集合中的多个多量子比特模式。值得注意的是，它们的光谱宽度比相应自旋共振的非均匀展宽小一个数量级。通过将 Ramsey 干涉测量应用于这些自旋多量子比特，我们实现了 600 kHz 的光谱选择性和 30 kHz 的光谱分辨率。作为实际结果，我们展示了对热噪声和应变波动不敏感的绝对直流磁强计。 显示英文摘要

摘要： Quantum bit or qubit is a two-level system, which builds the foundation for quantum computation, simulation, communication and sensing. Quantum states of higher dimension, i.e., qutrits (D = 3) and especially qudits (D = 4 or higher), offer significant advantages. Particularly, they can provide noise-resistant quantum cryptography, simplify quantum logic and improve quantum metrology. Flying and solid-state qudits have been implemented on the basis of photonic chips and superconducting circuits, respectively. However, there is still a lack of room-temperature qudits with long coherence time and high spectral resolution. The silicon vacancy centers in silicon carbide (SiC) with spin S = 3/2 are quite promising in this respect, but until now they were treated as a canonical qubit system. Here, we apply a two-frequency protocol to excite and image multiple qudit modes in a SiC spin ensemble under ambient conditions. Strikingly, their spectral width is about one order of magnitude narrower than the inhomogeneous broadening of the corresponding spin resonance. By applying Ramsey interferometry to these spin qudits, we achieve a spectral selectivity of 600 kHz and a spectral resolution of 30 kHz. As a practical consequence, we demonstrate absolute DC magnetometry insensitive to thermal noise and strain fluctuations.