Abstract
Superpositions of states with macroscopically different properties, named ‘cats’ after Schrödinger’s Gedanken experiment, are extraordinarily sensitive probes of their environment. They can be used to investigate the decoherence mechanism and the quantum-to-classical transition1,2,3,4,5, as well as to realize quantum-enabled sensors6 with promising applications. We report here the creation of a ‘circular cat’, namely an atom in a superposition of two circular Rydberg states with huge opposite magnetic momenta. It is an exquisite probe of the magnetic field, able to perform a single-shot detection of a 13 nT field in only 20 μs. This single-atom cat is as sensitive as a set of 1,800 ordinary atoms, demonstrating the usefulness of Rydberg state engineering for quantum-enabled technologies.
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Data availability
The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
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Acknowledgements
The authors thank Ch. Koch and S. Patsch for useful discussions. The authors acknowledge financial support from the European Union under the Research and Innovation action project ‘RYSQ’ (640378) and from the Agence Nationale de la Recherche under project ‘SNOCAR’ (167754).
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E.K.D., A.L., J.M.R., S.H., M.B. and S.G. contributed to the experimental set-up. E.K.D. and A.L. collected the data and analysed the results. S.G. supervised the experiment. All authors discussed the results and the manuscript.
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Dietsche, E.K., Larrouy, A., Haroche, S. et al. High-sensitivity magnetometry with a single atom in a superposition of two circular Rydberg states. Nat. Phys. 15, 326–329 (2019). https://doi.org/10.1038/s41567-018-0405-4
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DOI: https://doi.org/10.1038/s41567-018-0405-4
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