Letter | Published:

Wheeler's delayed-choice gedanken experiment with a single atom

Nature Physics volume 11, pages 539542 (2015) | Download Citation

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Abstract

The wave–particle dual nature of light and matter and the fact that the choice of measurement determines which one of these two seemingly incompatible behaviours we observe are examples of the counterintuitive features of quantum mechanics. They are illustrated by Wheeler’s famous ‘delayed-choice’ experiment1, recently demonstrated in a single-photon experiment2. Here, we use a single ultracold metastable helium atom in a Mach–Zehnder interferometer to create an atomic analogue of Wheeler’s original proposal. Our experiment confirms Bohr’s view that it does not make sense to ascribe the wave or particle behaviour to a massive particle before the measurement takes place1. This result is encouraging for current work towards entanglement and Bell’s theorem tests in macroscopic systems of massive particles3.

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Change history

  • 03 June 2015

    In the version of this Letter originally published, a sentence in the text describing the points in Fig. 3 was incorrect and should have read: 'The distinction between the removal (blue points) and application (red points) of the mixing π/2 pulse is very clear, as the former is ~50% irrespective of the phase ϕ, while the latter shows the expected sinusoidal dependence on ϕ, typical of a Mach–Zehnder interferometer.' This has now been corrected in all versions of the Letter.

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Acknowledgements

A.G.T. acknowledges the support of the Australian Research Council through the Future Fellowship grant FT100100468. The authors would like to acknowledge the technical assistance of C. Dedman as well as C. Savage for informative discussions.

Author information

Affiliations

  1. Research School of Physics and Engineering, Australian National University, Canberra ACT 0200, Australia

    • A. G. Manning
    • , R. I. Khakimov
    • , R. G. Dall
    •  & A. G. Truscott

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Contributions

A.G.M., R.G.D. and A.G.T. conceived the experiment. A.G.M. and R.I.K. performed the experiment and R.I.K. collected the data presented in this Letter. All authors contributed to the conceptual formulation of the physics, the interpretation of the data and writing the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to A. G. Truscott.

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DOI

https://doi.org/10.1038/nphys3343

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