beecee Posted November 30, 2018 Share Posted November 30, 2018 https://phys.org/news/2018-11-probing-quantum-physics-macroscopic-scale.html Why does quantum mechanics work so well for microscopic objects, yet macroscopic objects are described by classical physics? This question has bothered physicists since the development of quantum theory more than 100 years ago. Researchers at Delft University of Technology and the University of Vienna have now devised a macroscopic system that exhibits entanglement between mechanical phonons and optical photons. They tested the entanglement using a Bell test, one of the most convincing and important tests to show a system behaves non-classically. Ever since its inception more than 100 years ago, physicists realized that quantum theory might be in conflict with some of the basic axioms of classical physics. In particular, the principles in question are if information can be exchanged faster than the speed of light (called 'locality'), and whether physical quantities exist regardless of whether they are observed or not (called 'realism').Albert Einstein once famously asked Abraham Pais, his biographer, if he really thought the moon only existed when he looked at it. Read more at: https://phys.org/news/2018-11-probing-quantum-physics-macroscopic-scale.html#jCp <<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> the paper: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.220404 Optomechanical Bell Test: ABSTRACT: Over the past few decades, experimental tests of Bell-type inequalities have been at the forefront of understanding quantum mechanics and its implications. These strong bounds on specific measurements on a physical system originate from some of the most fundamental concepts of classical physics—in particular that properties of an object are well-defined independent of measurements (realism) and only affected by local interactions (locality). The violation of these bounds unambiguously shows that the measured system does not behave classically, void of any assumption on the validity of quantum theory. It has also found applications in quantum technologies for certifying the suitability of devices for generating quantum randomness, distributing secret keys and for quantum computing. Here we report on the violation of a Bell inequality involving a massive, macroscopic mechanical system. We create light-matter entanglement between the vibrational motion of two silicon optomechanical oscillators, each comprising approx. 1010 atoms, and two optical modes. This state allows us to violate a Bell inequality by more than 4 standard deviations, directly confirming the nonclassical behavior of our optomechanical system under the fair sampling assumption. <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>> https://physics.aps.org/synopsis-for/10.1103/PhysRevLett.121.220404 Synopsis: Quantum Entanglement With 10 Billion Atoms: Researchers have experimentally demonstrated two cornerstones of quantum physics—entanglement and Bell inequality violations—with two macroscopic mechanical resonators Link to comment Share on other sites More sharing options...
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