Detecting spins by their fluorescence with a microwave photon counter
Detecting spins by their fluorescence with a microwave photon counter
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DOI：
10.1038/s41586-021-04076-z
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发表时间：
2021-12-16
期刊：
影响因子：
64.8
通讯作者：
Flurin, Emmanuel
中科院分区：
文献类型：
--
作者：
Albertinale, Emanuele;Balembois, Leo;Flurin, Emmanuel
量子发射器通过辐射部分吸收的能量来响应共振照明。该辐射场的一个分量与驱动音相位相干，而另一个分量是不相干的，由自发发射的光子组成，形成荧光信号（1）。原子、分子和色心通常通过它们在光学频率下的荧光来检测，在量子技术（2，3）和显微镜（4-7）中有重要的应用。相比之下，电子自旋通常通过它们响应于微波驱动脉冲而发射的相位相干回波来检测（8）。它们辐射的非相干部分--在单个自旋弛豫事件后自发发射的微波光子流--由于自旋辐射衰减率低和缺乏单微波光子探测器（SMPD），迄今为止还没有被观察到。在这里，使用超导量子器件，我们证明了在微波频率和毫开尔文温度下通过荧光检测硅中的施主自旋的小集合。我们通过将它们耦合到高品质因数和小模式体积的超导谐振器来提高它们的辐射衰减率，并且我们将设备输出连接到新开发的基于超导量子位的SMPD 10。此外，我们表明，SMPD可用于检测自旋回波和标准的自旋表征测量（拉比章动和光谱）可以实现与回波和荧光检测。我们讨论了潜在的SMPD检测作为一种方法的磁共振波谱的小数目的自旋。
Quantum emitters respond to resonant illumination by radiating part of the absorbed energy. A component of this radiation field is phase coherent with the driving tone, whereas another component is incoherent and consists of spontaneously emitted photons, forming the fluorescence signal(1). Atoms, molecules and colour centres are routinely detected by their fluorescence at optical frequencies, with important applications in quantum technology(2,3) and microscopy(4-7). By contrast, electron spins are usually detected by the phase-coherent echoes that they emit in response to microwave driving pulses(8). The incoherent part of their radiation-a stream of microwave photons spontaneously emitted upon individual spin relaxation events-has not been observed so far because of the low spin radiative decay rate and of the lack of single microwave photon detectors (SMPDs). Here using superconducting quantum devices, we demonstrate the detection of a small ensemble of donor spins in silicon by their fluorescence at microwave frequencies and millikelvin temperatures. We enhance their radiative decay rate by coupling them to a high-quality-factor and small-mode-volume superconducting resonator(9), and we connect the device output to a newly developed SMPD10 based on a superconducting qubit. In addition, we show that the SMPD can be used to detect spin echoes and that standard spin characterization measurements (Rabi nutation and spectroscopy) can be achieved with both echo and fluorescence detection. We discuss the potential of SMPD detection as a method for magnetic resonance spectroscopy of small numbers of spins.