摘要
高分辨率宽频谱测量技术在天文学、无线通信、医学成像等领域具有重要应用价值.金刚石氮-空位(nitro-gen-vacancy,NV)色心因其高稳定性、高灵敏度、实时监测、单点探测以及适用于长时间测量等特性已成为频谱分析仪备受关注的选择.目前,基于NV色心作为探测器的宽频谱分析仪能够在几十GHz频带内进行实时频谱分析,然而其频率分辨率仅达到MHz水平.本文通过搭建结合连续外差技术的量子金刚石微波频谱成像系统,利用磁场梯度对NV色心谐振频率进行空间编码,成功获取了 900 MHz—6.0 GHz范围内完整的频谱数据.在可测频谱范围内,系统进一步采用连续外差的方法,同时施加谐振微波和轻微失谐的辅助微波对NV色心进行有效激发,增强了NV磁强计对微弱微波信号的响应.该方法使系统在可测频谱范围内实现了1Hz的频率分辨率,并能够对间隔为 1 MHz扫频步进的多个频点的频率分辨率进行单独测量.以上研究结果表明基于NV色心的宽频谱测量可实现Hz级频率分辨,为未来的频谱分析和应用提供了有力的技术支持.
Abstract
High-resolution wide-spectrum measurement techniques have important applications in fields such as astronomy,wireless communication,and medical imaging.Nitrogen-vacancy(NV)center in diamond is well known for its high stability,high sensitivity,real-time monitoring,single-point detection,and suitability for long-term measurement,and has an outstanding choice for spectrum analyzers.Currently,spectrum analyzers based on NV centers as detectors can perform real-time spectrum analysis in the range of several tens of gigahertz,but their frequency resolution is limited to a MHz level.In this study,we construct a quantum diamond microwave spectrum imaging system by combining continuous wave-mixing techniques.According to the spin-related properties of the NV center in diamond,we implement optical pumping by 532 nm green laser light illuminating the diamond NV center.A spherical magnet is used to produce a magnetic field gradient along the direction of the diamond crystal.By adjusting the size and direction of the magnetic field gradient,spatial encoding of the resonance frequency of the NV center is achieved.The magnetic field gradient induces the Zeeman effect on the diamond surface at different positions,generating corresponding ODMR signals.Through accurate programming,we coordinate the frequency scanning step size of the microwave source with the camera exposure and image storage time,and synchronize them circularly according to the order of image acquisition.Ultimately,after algorithmic processing,we successfully obtain comprehensive spectrum data in a range from 900 MHz to 6.0 GHz.Within the measurable spectrum range,the system employs continuous wave-mixing,simultaneously applying resonant microwaves and slightly detuning auxiliary microwaves to effectively excite the NV center.This method triggers off microwave interference effects,disrupting the balance between laser-induced polarization and microwave-induced spontaneous relaxation.Specifically,microwave interference causes the phase and amplitude of the fluorescence signal to change,leading to the generation of alternating current fluorescence signals.This further enhances the response of the NV magnetometer to weak microwave signals.The method enables the system to achieve a frequency resolution of 1 Hz in the measurable spectrum range,and it can separately measure the frequency resolution of multiple frequency points with a frequency step size of 1 MHz.The research results indicate that the wide-spectrum measurement based on NV centers can achieve sub-hertz frequency resolution,providing robust technical support for future spectrum analysis and applications.
基金项目
国防基础科学研究计划()
国家自然科学基金国际(地区)合作与交流项目(62220106012)
山西省杰出青年基金(202103021221007)
山西省"1331工程"重点学科建设项目(1331KSC)
维普
万方数据