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  • Brief Communications Arising
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Verifying quantum superpositions at metre scales

Nature volume 537, pages E1–E2 (2016)Cite this article

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ARISING FROM T. Kovachy et al. Nature 528, 530–533 (2015); doi: 10.1038/nature16155

Although the existence of quantum superpositions of massive particles over microscopic separations has been established since the founding of quantum mechanics, the maintenance of superposition states over macroscopic separations is a subject of modern experimental tests. Kovachy et al.1 report on applying optical pulses to place a freely falling Bose–Einstein condensate into a superposition of two trajectories that separate by an impressive distance of 54 cm before being redirected towards one another. When the trajectories overlap, a final optical pulse produces interference with high contrast, but random phase, between the two wave packets. Contrary to ref. 1, we argue that the observed interference is consistent with, but does not prove, the claim that the spatially separated atomic ensembles were in a quantum superposition state; therefore, the persistence of such superposition states remains experimentally unestablished. There is a Reply to this Brief Communication Arising by Kovachy, T. et al. Nature 537, http://dx.doi.org/10.1038/nature19109 (2016).

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Authors and Affiliations

  1. Department of Physics, University of California, Berkeley, 94720, California, USA

    D. M. Stamper-Kurn & H. Müller

  2. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, 94720, California, USA

    D. M. Stamper-Kurn

  3. JILA, National Institute of Standards and Technology and University of Colorado, Boulder, 80309, Colorado, USA

    G. E. Marti

Authors
  1. D. M. Stamper-Kurn
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  2. G. E. Marti
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  3. H. Müller
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All authors contributed to the study and to the writing of the Brief Communication Arising.

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Correspondence to D. M. Stamper-Kurn.

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Stamper-Kurn, D., Marti, G. & Müller, H. Verifying quantum superpositions at metre scales. Nature 537, E1–E2 (2016). https://doi.org/10.1038/nature19108

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