Spins are prototypical systems with the potential to probe magnetic fields down to the atomic scale limit. Exploiting their quantum nature through appropriate sensing protocols allows to enlarge their applicability to fields not always accessible by classical sensors. Here we first show that quantum sensing protocols for AC magnetic fields can be implemented with molecular spin ensembles embedded into hybrid quantum circuits. We then show that, using only echo detection at microwave frequency and no optical readout, Dynamical Decoupling protocols synchronized with the AC magnetic fields can enhance sensitivity up to S ≈ 10⁻¹⁰ − 10⁻⁹ T Hz^−1/2 with a low (4-5) number of applied pulses. These results paves the way for the development of strategies to exploit molecular spins as quantum sensors.

自旋是典型的系统，具有探测低至原子尺度极限的磁场的潜力。通过适当的传感协议利用它们的量子特性，可以将它们的适用性扩大到传统传感器无法总是访问的领域。在这里，我们首先展示了交流磁场的量子传感协议可以通过嵌入混合量子电路的分子自旋系综来实现。然后我们表明，仅使用微波频率的回波检测而不使用光学读出，与交流磁场同步的动态去耦协议可以将灵敏度提高到S  ≈ 10 ⁻¹⁰  − 10 ⁻⁹  T Hz ^−1/2，且具有低 ( 4-5) 施加的脉冲数。这些结果为开发利用分子自旋作为量子传感器的策略铺平了道路。