The nitrogen-vacancy (NV) center in diamond is an ideal candidate for quantum sensing because of its excellent spin coherence property as well as the possibility for optical initialization and readout. Previous studies, on the other hand, have typically been conducted at low or room temperature. The inability to fully understand the coherence properties of the NV center at high temperatures limits NV's further applications. We systematically investigate the coherence properties of NV center ensemble at temperatures ranging from 300 K to 600 K in this paper. Coherence time $T_2$ decreases rapidly from $184\mu \text{s}$ at 300 K to $30\mu \text{s}$ at 600 K due to the interaction with paramagnetic impurities. At all experiment temperatures, both single-quantum and double-quantum transitions exhibit a $T^5$ relaxation rate, which is attributed to the two-phonon Raman process. Nonetheless, the inhomogeneous dephasing time $T_2^{*}$ and thermal-echo decoherence time $T_{\text{TE}}$ remain almost unchanged at temperature up to 600 K. A thermal-echo-based thermometer is demonstrated to have a sensitivity of $41\text{mK}/\sqrt{\mathrm{Hz}}$ at 450 K. These findings will pave the way for NV-based high-temperature sensing and provide a more comprehensive understanding of solid-state qubit decoherence.

中文翻译：

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金刚石中 NV 系综的温度相关相干特性高达 600 K

金刚石中的氮空位 (NV) 中心是量子传感的理想候选者，因为它具有出色的自旋相干特性以及光学初始化和读出的可能性。另一方面，以前的研究通常是在低温或室温下进行的。无法完全理解高温下 NV 中心的相干特性限制了 NV 的进一步应用。在本文中，我们系统地研究了 NV 中心系综在 300 K 到 600 K 温度范围内的相干特性。相干时间${吨}_2$ 从迅速减少 $184\mu \text{秒}$ 在 300 K 到 $30\mu \text{秒}$由于与顺磁性杂质的相互作用，在 600 K 时。在所有实验温度下，单量子和双量子跃迁都表现出${吨}^5$弛豫率，这归因于双声子拉曼过程。尽管如此，不均匀的移相时间${吨}_2^{*}$ 和热回波退相干时间 ${吨}_{\text{TE}}$ 在高达 600 K 的温度下几乎保持不变。 $41\text{MK}/\sqrt{\mathrm{赫兹}}$ 在 450 K。这些发现将为基于 NV 的高温传感铺平道路，并提供对固态量子位退相干的更全面的理解。