--- res: bibo_abstract: - Mechanical systems facilitate the development of a hybrid quantum technology comprising electrical, optical, atomic and acoustic degrees of freedom1, and entanglement is essential to realize quantum-enabled devices. Continuous-variable entangled fields—known as Einstein–Podolsky–Rosen (EPR) states—are spatially separated two-mode squeezed states that can be used for quantum teleportation and quantum communication2. In the optical domain, EPR states are typically generated using nondegenerate optical amplifiers3, and at microwave frequencies Josephson circuits can serve as a nonlinear medium4,5,6. An outstanding goal is to deterministically generate and distribute entangled states with a mechanical oscillator, which requires a carefully arranged balance between excitation, cooling and dissipation in an ultralow noise environment. Here we observe stationary emission of path-entangled microwave radiation from a parametrically driven 30-micrometre-long silicon nanostring oscillator, squeezing the joint field operators of two thermal modes by 3.40 decibels below the vacuum level. The motion of this micromechanical system correlates up to 50 photons per second per hertz, giving rise to a quantum discord that is robust with respect to microwave noise7. Such generalized quantum correlations of separable states are important for quantum-enhanced detection8 and provide direct evidence of the non-classical nature of the mechanical oscillator without directly measuring its state9. This noninvasive measurement scheme allows to infer information about otherwise inaccessible objects, with potential implications for sensing, open-system dynamics and fundamental tests of quantum gravity. In the future, similar on-chip devices could be used to entangle subsystems on very different energy scales, such as microwave and optical photons.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Shabir foaf_name: Barzanjeh, Shabir foaf_surname: Barzanjeh foaf_workInfoHomepage: http://www.librecat.org/personId=2D25E1F6-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0003-0415-1423 - foaf_Person: foaf_givenName: Elena foaf_name: Redchenko, Elena foaf_surname: Redchenko foaf_workInfoHomepage: http://www.librecat.org/personId=2C21D6E8-F248-11E8-B48F-1D18A9856A87 - foaf_Person: foaf_givenName: Matilda foaf_name: Peruzzo, Matilda foaf_surname: Peruzzo foaf_workInfoHomepage: http://www.librecat.org/personId=3F920B30-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0002-3415-4628 - foaf_Person: foaf_givenName: Matthias foaf_name: Wulf, Matthias foaf_surname: Wulf foaf_workInfoHomepage: http://www.librecat.org/personId=45598606-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0001-6613-1378 - foaf_Person: foaf_givenName: Dylan foaf_name: Lewis, Dylan foaf_surname: Lewis - foaf_Person: foaf_givenName: Georg M foaf_name: Arnold, Georg M foaf_surname: Arnold foaf_workInfoHomepage: http://www.librecat.org/personId=3770C838-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0003-1397-7876 - foaf_Person: foaf_givenName: Johannes M foaf_name: Fink, Johannes M foaf_surname: Fink foaf_workInfoHomepage: http://www.librecat.org/personId=4B591CBA-F248-11E8-B48F-1D18A9856A87 orcid: 0000-0001-8112-028X bibo_doi: 10.1038/s41586-019-1320-2 bibo_volume: 570 dct_date: 2019^xs_gYear dct_identifier: - UT:000472860000042 dct_language: eng dct_publisher: Nature Publishing Group@ dct_title: Stationary entangled radiation from micromechanical motion@ ...