Fully controllable ultracold atomic systems are creating opportunities for quantum sensing, yet demonstrating a quantum advantage in useful applications by harnessing entanglement remains a challenging task. Here, we realize a many-body quantum-enhanced sensor to detect displacements and electric fields using a crystal of ~150 trapped ions. The center-of-mass vibrational mode of the crystal serves as a high-Q mechanical oscillator, and the collective electronic spin serves as the measurement device. By entangling the oscillator and collective spin and controlling the coherent dynamics via a many-body echo, a displacement is mapped into a spin rotation while avoiding quantum back-action and thermal noise. We achieve a sensitivity to displacements of 8.8 ± 0.4 decibels below the standard quantum limit and a sensitivity for measuring electric fields of 240 ± 10 nanovolts per meter in 1 second. Feasible improvements should enable the use of trapped ions in searches for dark matter.

完全可控的超冷原子系统正在为量子传感创造机会，但通过利用纠缠在有用应用中展示量子优势仍然是一项具有挑战性的任务。在这里，我们实现了一个多体量子增强传感器，使用约 150 个被捕获离子的晶体来检测位移和电场。晶体的质心振动模式用作高Q机械振荡器，集体电子自旋作为测量装置。通过纠缠振荡器和集体自旋并通过多体回波控制相干动力学，将位移映射为自旋旋转，同时避免量子反作用和热噪声。我们实现了对低于标准量子极限 8.8 ± 0.4 分贝的位移的灵敏度，以及在 1 秒内测量每米 240 ± 10 纳伏的电场的灵敏度。可行的改进应该能够在暗物质搜索中使用俘获离子。