Spin-based probes of magnetic dynamics in the few-magnon regime

孤立自旋，量子化磁矩的基本粒子提供了一个独特的敏感和纳米级的探针磁场和磁性材料。特别是，与氮空位（NV）中心相关的长寿命自旋（金刚石中的光学活性缺陷）与磁场的调谐非常精细，以至于它应该能够探测近端铁磁体中所谓的磁振子的量子零点波动，并观察绝对磁振子温度测量中磁振子吸收和发射的量子不对称性。这种基于nv的传感器为磁性材料的热力学打开了一扇新的窗口，并将允许我们探索通过自旋电流注入来冷却磁振子的极限，这目前仍然是未知的。******与此同时，自旋和磁性材料之间的相互作用代表了量子信息科学的一种资源：已经提出了磁振子来介导自旋量子比特之间强的、可控的相互作用。仔细研究NV自旋与近基态磁振子槽相互作用的演化，应该会揭示自旋-磁振子纠缠的特征，这是实现量子信息磁振子介导门的第一步。这样的体系结构可以将固态自旋的长相干时间与比现代超导系统密度大几个数量级的量子比特间距结合起来，为未来量子信息处理在优化、分子模拟等方面的应用开辟了一条道路，使加拿大的企业和政府受益。******要进行这样的实验，需要将能够分离和检测NV自旋的共聚焦显微镜与能够保持样品温度接近或低于磁激发量子~ 150 mK的稀释冰箱相结合。我们的合作已经获得了共聚焦显微镜和稀释冰箱；该RTI提案将资助将它们集成到单个实验中所需的组件。需要一种特殊的低温兼容显微镜物镜和低温纳米定位器来取代它们的室温对应物；微波和直流电子线路必须小心地安装在低温恒温器中，以控制样品和定位器；光学元件将引导激发和荧光进出低温恒温器；自定义安装将支持样品和组件。因此，所要求的设备利用相当多的现有资源来创建一个高度专业化的设备，能够在纳米磁学和量子磁学方面进行前沿研究。

Isolated spins the quantized magnetic moments of fundamental particles offer a uniquely sensitive and nanoscale probe of magnetic fields and magnetic materials. In particular, the long-lived spin associated with the nitrogen-vacancy (NV) centre, an optically active defect in diamond, is so exquisitely attuned to magnetic fields that it should be able to detect the quantum zero point fluctuations of magnetic excitations so-called magnons in a proximal ferromagnet, and observe the quantum asymmetry in magnon absorption and emission for absolute magnon thermometry. Such an NV-based sensor opens a new window into the thermodynamics of magnetic materials, and will permit us to explore the limits to magnon cooling via spin current injection, which currently remain unknown. ******At the same time, interactions between spins and magnetic materials represent a resource for quantum information science: magnons have been proposed to mediate strong, controllable interactions between spin qubits. Careful investigation of the evolution of an NV spin interacting with a near-ground state magnon bath should reveal signatures of spin-magnon entanglement, representing the first step towards realization of magnon-mediated gates for quantum information. Such an architecture could combine the long coherence times available in solid-state spins with a qubit spacing orders of magnitude denser than modern superconducting systems, potentially opening an avenue for future quantum information processing applications in optimization, molecular simulation and others, benefitting Canadian business and government.******To pursue such experiments requires combining a confocal microscope capable of isolating and detecting NV spins with a dilution refrigerator capable of maintaining a sample temperature near or below the quantum of magnetic excitation ~ 150 mK. Our collaboration already has access to a confocal microscope and a dilution refrigerator; this RTI proposal would fund the components needed to integrate them into a single experiment. A specialty cryogenically-compatible microscope objective and cryogenic nano-positioners are needed to replace their room-temperature counterparts; microwave and DC electronic lines must be carefully installed in the cryostat to control the sample and positioners; optical components will route excitation and fluorescence into and out of the cryostat; custom mounts will support the sample and components. The requested equipment thus leverages considerable existing resources to create a highly specialized apparatus capable of pursuing cutting edge research in nanomagnetism and quantum magnonics.