Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors because of their long spin coherence time under ambient conditions. However, their spin resonances are relatively insensitive to non-magnetic parameters such as temperature. A magnetic-nanoparticle-nanodiamond hybrid thermometer, where the temperature change is converted to the magnetic field variation near the Curie temperature, were demonstrated to have enhanced temperature sensitivity (⁠|$11{\rm{\,\,mK\,\,H}}{{\rm{z}}^{ - 1/2}}$|⁠) (Wang N, Liu G-Q and Leong W-H et al. Phys Rev X 2018; 8: 011042), but the sensitivity was limited by the large spectral broadening of ensemble spins in nanodiamonds. To overcome this limitation, here we show an improved design of a hybrid nanothermometer using a single NV center in a diamond nanopillar coupled with a single magnetic nanoparticle of copper-nickel alloy, and demonstrate a temperature sensitivity of |$76{\rm{\,\,\mu K\,\,H}}{{\rm{z}}^{ - 1/2}}$|⁠. This hybrid design enables detection of 2 mK temperature changes with temporal resolution of 5 ms. The ultra-sensitive nanothermometer offers a new tool to investigate thermal processes in nanoscale systems.

中文翻译：

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超灵敏混合金刚石纳米温度计

金刚石中的氮空位 (NV) 中心是很有前途的量子传感器，因为它们在环境条件下自旋相干时间长。然而，它们的自旋共振对温度等非磁性参数相对不敏感。磁性-纳米粒子-纳米金刚石混合温度计，其中温度变化转换为居里温度附近的磁场变化，被证明具有增强的温度敏感性（⁠|$11{\rm{\,\,mK\,\,H }} {{\ RM {Z}} ^ { - 1/2}} $ |⁠）（汪嗯，刘GQ和丰隆WH等。物理学版本X2018 年；8: 011042)，但灵敏度受到纳米金刚石中系综自旋光谱展宽的限制。为了克服这一限制，我们展示了一种改进的混合纳米温度计设计，该设计使用金刚石纳米柱中的单个 NV 中心与铜镍合金的单个磁性纳米颗粒相结合，并展示了|$76{\rm{\, \,\mu K\,\,H}}{{\rm{z}}^{ - 1/2}}$|⁠。这种混合设计能够以 5 ms 的时间分辨率检测 2 mK 的温度变化。超灵敏纳米温度计为研究纳米级系统中的热过程提供了一种新工具。