Direct observation of deterministic macroscopic entanglement

TLDR

Quantum entanglement of mechanical systems arises when distinct objects exhibit such strong correlations that they cannot be described independently, yet observing it becomes increasingly difficult as mass grows due to the need for extremely precise measurement and control. The study aims to deterministically entangle two 70‑pg mechanical drumheads using pulsed electromechanics. The authors employ pulsed electromechanical techniques to generate and control the entanglement between the drumheads. Quantum state tomography of the drums’ position and momentum quadratures reveals direct entanglement, demonstrating that such macroscopic systems can be used for fundamental tests, surpass the standard quantum limit in sensing, and serve as long‑lived nodes in future quantum networks.

Abstract

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 pg. 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 uniquely 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.