Moving beyond the conventional limits imposed by quantum mechanics, two studies demonstrate quantum entanglement in macroscopic mechanical oscillators and show how precise measurement of quantum-mechanical momentum can be achieved without disruption. Quantum engagement of mechanical systems emerges when two separate and distinct objects move with such a high degree of similarity that they can no longer be described as either distinct or separate from one another. Previously, observations of this and other quantum mechanics have generally been limited to microscopic quantum scales, such as small numbers of single ions, atoms and photons. Theoretically, however, quantum mechanics also applies to objects of all sizes. In this pair of studies, Shlomi Kotler and colleagues, and Laure Mercier de Lépinay and colleagues, report experimental examples of the direct observation of two macroscopic-scale quantum phenomena and demonstrate the ability to extend measurements of quantum states to macroscopic systems. In their report, Kotler et al. present evidence of quantum entanglement using a pair of macroscale vibrating membranes. While ostensibly tiny (the membranes measured about 10 microns in diameter and weighed about 100 picograms each), they are far more massive than the examples of previously entangled objects. Mercier de Lépinay et al. used similar macroscopic mechanical oscillators to show how it is possible to measure entanglement without disturbing quantum-mechanical momentum. In addition to demonstrating direct evidence of quantum entanglement and measurement beyond the conventional limits imposed by quantum mechanics, the approaches of both groups could have a broader implication on quantum computing and enhanced measurements of fundamental physics, write Hoi-Kwan Lau and Aashish Clerk in a related Perspective. "Apart from practical applications, these experiments address how far into the macroscopic realm experiments can push quantum phenomena," Lau and Clerk write.
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Journal
Science