Wang Hanfeng, Tiwari Kunal L, Jacobs Kurt, Judy Michael, Zhang Xin, Englund Dirk R, Trusheim Matthew E
Massachusetts Institute of Technology, Cambridge, MA, USA.
MIT Lincoln Laboratory, Lexington, MA, USA.
Nat Commun. 2024 Nov 28;15(1):10320. doi: 10.1038/s41467-024-54333-8.
Quantum sensors based on solid-state defects, in particular nitrogen-vacancy (NV) centers in diamond, enable precise measurement of magnetic fields, temperature, rotation, and electric fields. Cavity quantum electrodynamic (cQED) readout, in which an NV ensemble is hybridized with a microwave mode, can overcome limitations in optical spin detection and has resulted in leading magnetic sensitivities at the pT-level. This approach, however, remains far from the intrinsic spin-projection noise limit due to thermal Johnson-Nyquist noise and spin saturation effects. Here we tackle these challenges by combining recently demonstrated spin refrigeration techniques with comprehensive nonlinear modeling of the cQED sensor operation. We demonstrate that the optically-polarized NV ensemble simultaneously provides magnetic sensitivity and acts as a heat sink for the deleterious thermal microwave noise background, even when actively probed by a microwave field. Optimizing the NV-cQED system, we demonstrate a broadband sensitivity of 576 ± 6 fT/ around 15 kHz in ambient conditions. We then discuss the implications of this approach for the design of future magnetometers, including near-projection-limited devices approaching 3 fT/ sensitivity enabled by spin refrigeration.
基于固态缺陷的量子传感器，特别是金刚石中的氮空位（NV）中心，能够精确测量磁场、温度、旋转和电场。腔量子电动力学（cQED）读出技术，即将NV系综与微波模式相结合，可以克服光学自旋检测的局限性，并在皮特斯拉（pT）水平上实现了领先的磁灵敏度。然而，由于热约翰逊-奈奎斯特噪声和自旋饱和效应，这种方法仍远未达到固有自旋投影噪声极限。在这里，我们通过将最近展示的自旋制冷技术与cQED传感器操作的全面非线性建模相结合来应对这些挑战。我们证明，即使在被微波场主动探测时，光学极化的NV系综也能同时提供磁灵敏度，并作为有害热微波噪声背景的散热器。通过优化NV-cQED系统，我们在环境条件下展示了在15 kHz左右576±6 fT/√Hz的宽带灵敏度。然后，我们讨论了这种方法对未来磁力计设计的影响，包括通过自旋制冷实现接近3 fT/√Hz灵敏度的近投影极限设备。
