Quantum mechanics-free subsystem with mechanical oscillators

Laure Mercier de Lépinay, Caspar F. Ockeloen-Korppi, Matthew J. Woolley, Mika A. Sillanpää

Research output: Contribution to journalArticleScientificpeer-review

60 Citations (Scopus)


Quantum mechanics sets a limit for the precision of continuous measurement of the position of an oscillator. We show how it is possible to measure an oscillator without quantum back-action of the measurement by constructing one effective oscillator from two physical oscillators. We realize such a quantum mechanics-free subsystem using two micromechanical oscillators, and show the measurements of two collective quadratures while evading the quantum back-action by 8 decibels on both of them, obtaining a total noise within a factor of 2 of the full quantum limit. This facilitates the detection of weak forces and the generation and measurement of nonclassical motional states of the oscillators. Moreover, we directly verify the quantum entanglement of the two oscillators by measuring the Duan quantity 1.4 decibels below the separability bound.

Original languageEnglish
Pages (from-to)625-629
Number of pages23
JournalScience (New York, N.Y.)
Issue number6542
Publication statusPublished - 7 May 2021
MoE publication typeA1 Journal article-refereed


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