Entanglement is an essential property of multipartite quantum systems, characterized by the inseparability of quantum states of objects regardless of their spatial separation. Generation of entanglement between increasingly macroscopic and disparate systems is an ongoing effort in quantum science, as it enables hybrid quantum networks, quantum-enhanced sensing and probing of the fundamental limits of quantum theory. The disparity of hybrid systems and the vulnerability of quantum correlations have thus far hampered the generation of macroscopic hybrid entanglement. Here, we generate an entangled state between the motion of a macroscopic mechanical oscillator and a collective atomic spin oscillator, as witnessed by an Einstein–Podolsky–Rosen variance below the separability limit, 0.83 ± 0.02 < 1. The mechanical oscillator is a millimetre-size dielectric membrane and the spin oscillator is an ensemble of 10⁹ atoms in a magnetic field. Light propagating through the two spatially separated systems generates entanglement because the collective spin plays the role of an effective negative-mass reference frame and provides—under ideal circumstances—a back-action-free subspace; in the experiment, quantum back-action is suppressed by 4.6 dB.

纠缠是多部分量子系统的基本属性，其特征是无论空间间隔如何，物体的量子态都是不可分割的。越来越多的宏观系统和不同系统之间的纠缠是量子科学领域的一项持续性工作，因为它可以实现混合量子网络，量子增强的传感以及探测量子理论的基本极限。迄今为止，混合系统的差异和量子相关性的脆弱性已经阻碍了宏观混合纠缠的产生。在这里，我们在宏观机械振荡器和集体原子自旋振荡器的运动之间产生纠缠状态，这是由低于可分离性极限0.83±0.02 <1的爱因斯坦-波多尔斯基-罗森方差所证明的。磁场中有^9个原子。通过两个在空间上分开的系统传播的光会产生纠缠，因为集体自旋起着有效的负质量参考系的作用，并且在理想情况下提供了无背向子空间。在实验中，量子反作用被抑制了4.6 dB。