Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 picograms. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.

当不同的物体以如此高的相关性运动时，就会出现机械系统的量子纠缠，以至于无法再单独描述它们。尽管量子力学大概适用于所有大小的物体，但是随着质量的增加，直接观察纠缠变得具有挑战性，需要以很小的误差来进行测量和控制。在这里，我们使用脉冲机电技术确定性地纠缠了两个质量为70皮克的机械鼓面。通过对两个鼓的位置和动量正交进行近乎量子限制的测量，我们执行了量子态层析成像，从而直接观察到纠缠。这种纠缠的宏观系统有望在量子力学的基础测试中发挥作用，能够进行超出标准量子极限的传感，