近简并氮-空位色心系综中由亮-暗态混合实现的热测量
Thermometry in Near-Degenerate Nitrogen-Vacancy Ensembles Enabled by Bright-Dark-State Mixing
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中文总结 AI 辅助
本研究揭示近简并NV色心系综中亮-暗态混合使自旋回波产生温度敏感信号，提出四相正交读出方案，并评估LDD4B序列，为无偏置场环境下的脉冲测温提供新途径。
中文摘要 AI 辅助
氮-空位（NV）色心已成为高灵敏度空间分辨温度测量的平台。当|0⟩→|+1⟩和|0⟩→|-1⟩跃迁近似简并且拉比频率与跃迁分裂可比时，在脉冲温度测量协议中遇到的自旋动力学可能显著改变预期的温度相关相位累积。我们研究了这些三重态（|0⟩, |±1⟩）自旋动力学及其在这些条件下对脉冲测温协议的影响。我们发现，常规热回波时序在共模失谐下产生的温度敏感信号幅度可忽略不计。然而，我们发现标称自旋回波时序在共模失谐下产生可分辨的振荡，从而产生强的温度敏感载波信号。这种偏离预期协议行为的情况被三重态动力学的系综模型定性捕获，该模型支持显著的暗态泄漏作为温度敏感响应的合理解释。这种混合增强的热回波采用四相正交读出，可分辨带符号的振荡频率，并通过独立扫描微波载波频率和流体温度进行验证。我们进一步评估了四重聚焦脉冲（LDD4B）低场动力学去耦序列延长NV相干性的能力，发现虽然回波保持对共模失谐的敏感性，但有效相位累积间隔约为总演化时间的一半。这些发现可能支持脉冲NV测温在生物或移动应用中的使用，在这些应用中施加磁场偏置场不切实际且微波功率可能受限。
英文摘要
Nitrogen-vacancy (NV) centers have emerged as a highly sensitive platform for spatially resolved temperature measurements. When the $\lvert0\rangle\to\lvert+1\rangle$ and $\lvert0\rangle\to\lvert-1\rangle$ transitions are nearly degenerate and the Rabi frequency is comparable to the transition splitting, the spin dynamics encountered during pulsed protocols for temperature measurement can significantly alter the intended accumulation of temperature-dependent phase. We investigate these triplet ($\lvert0\rangle$, $\lvert\pm1\rangle$) spin dynamics and their effect on pulsed thermometry protocols under these conditions. We find that the conventional thermal-echo timing produces negligible temperature-sensitive signal amplitudes at the common-mode detuning. However, we find that the nominal spin-echo timing produces resolvable oscillations at the common-mode detuning, leading to a strong temperature-sensitive carrier signal. This departure from the expected protocol behavior is qualitatively captured by an ensemble model of the triplet dynamics, which supports significant dark-state leakage as a plausible mechanism for the temperature-sensitive response. This mixing-enabled thermal echo uses a four-phase quadrature readout that resolves the signed oscillation frequency and is validated using independent sweeps of the microwave carrier frequency and fluid temperature. We further assess the ability of a four-refocusing-pulse (LDD4B) low-field dynamical-decoupling sequence to extend the NV coherence and find that while the echo retains a sensitivity to common-mode detuning, the effective phase-accumulation interval corresponds to approximately half the total evolution time. These findings could support the use of pulsed NV thermometry in biological or mobile applications where applying magnetic bias fields is impractical and microwave power may be limited.
发表机构
- California Institute of Technology（加州理工学院）
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