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Quantum mechanics

Atoms that agree to differ

Nature volume 388, pages 827–829 (1997)Cite this article

In our everyday world, things have properties independent of whether we care to look at them or not. Whether a given apple is red or green is independent of our checking its colour. And although most people acknowledge that quantum mechanics is very strange, they often feel that quantum objects still have their properties — it seems to be just the clumsiness of our tools that invariably disturbs quantum object s in such a way that we cannot observe all their properties. But any seasoned quantum mechanic knows this not to be true. For example, physically separated objects can become ‘entangled’ in a collective state, each possessing no well-defined state of its own. Experimental observation of entanglement so far has been restricted to photons1, electrons and protons. But Hagley et al.2 have now demonstrated entangled pairs of atoms. In their experiment they produce pairs of atoms, one in the ground state and the other in an excited state, but it is completely undefined which is which.

Hagley and colleagues use a beam of rubidium atoms prepared in so-called circular Rydberg states. These are highly excited states in which the outermost electron is confined to an effectively circular orbit, very much like planets around the Sun. They use states with principal quantum number 50 and 51; the first they call the ground state for the experiment and the second one the excited state.

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References

  1. Aspect, A., Grangier, P. & Roger, G. Phys. Rev. Lett. 47, 460–463 (1981).

    Google Scholar 

  2. Hagley, E.et al. Phys. Rev. Lett. 79, 1–5 (1997).

    Google Scholar 

  3. Fry, E. S., Walther, T. & Li, S. Phys. Rev. A 52, 4381–4395 (1995).

    Google Scholar 

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Authors and Affiliations

  1. Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, A-6020, Innsbruck, Austria

    D. Bouwmeester & A. Zeilinger

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  1. D. Bouwmeester
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  2. A. Zeilinger
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Bouwmeester, D., Zeilinger, A. Atoms that agree to differ. Nature 388, 827–829 (1997). https://doi.org/10.1038/42134

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