Direct observation of deterministic macroscopic entanglement

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.

Automated summary

In this study, two mechanical drumheads with masses of 70 picograms were deterministically entangled using pulsed electromechanics. Quantum state tomography was performed through nearly quantum-limited measurements, allowing for the direct observation of entanglement. These entangled macroscopic systems are expected to be used in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes in future quantum networks.