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Photon-by-photon feedback control of a single-atom trajectory

Nature volume 462, pages 898–901 (2009)Cite this article

Abstract

Feedback is one of the most powerful techniques for the control of classical systems. An extension into the quantum domain is desirable as it could allow the production of non-trivial quantum states1,2,3,4 and protection against decoherence5,6. The difficulties associated with quantum, as opposed to classical, feedback arise from the quantum measurement process—in particular the quantum projection noise and the limited measurement rate—as well as from quantum fluctuations perturbing the evolution in a driven open system. Here we demonstrate real-time feedback control7,8,9,10,11,12 of the motion of a single atom trapped in an optical cavity. Individual probe photons carrying information about the atomic position13,14 activate a dipole laser that steers the atom on timescales 70 times shorter than the atom’s oscillation period in the trap. Depending on the specific implementation, the trapping time is increased by a factor of more than four owing to feedback cooling, which can remove almost all the kinetic energy of the atom in a quarter of an oscillation period12. Our results show that the detected photon flux reflects the atomic motion, and thus mark a step towards the exploration of the quantum trajectory15,16 of a single atom at the standard quantum limit.

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Figure 1: Experimental setup including the feedback loop.
Figure 2: Feedback protocol for a single-atom trajectory.
Figure 3: Manoeuvring of a single atom using real-time feedback.
Figure 4: Dynamics of atomic motion from photon correlation measurements.

References

  1. Shapiro, J. H., Saplakoglu, G., Ho, S.-T., Kumar, P. & Saleh, B. E. A. Theory of light detection in the presence of feedback. J. Opt. Soc. Am. B 4, 1604–1620 (1987)

    ADS  CAS  Article  Google Scholar 

  2. Wiseman, H. M. Quantum theory of continuous feedback. Phys. Rev. A 49, 2133–2150 (1994)

    ADS  CAS  Article  Google Scholar 

  3. Jacobs, K. How to project qubits faster using quantum feedback. Phys. Rev. A 67, 030301 (2003)

    ADS  Article  Google Scholar 

  4. Combes, J., Wiseman, H. M. & Jacobs, K. Rapid measurement of quantum systems using feedback control. Phys. Rev. Lett. 100, 160503 (2008)

    ADS  Article  Google Scholar 

  5. Viola, L., Knill, E. & Lloyd, S. Dynamical decoupling of open quantum systems. Phys. Rev. Lett. 82, 2417–2421 (1999)

    ADS  MathSciNet  CAS  Article  Google Scholar 

  6. Viola, L. Advances in decoherence control. J. Mod. Opt. 51, 2357–2367 (2004)

    ADS  Article  Google Scholar 

  7. Ashkin, A. & Dziedzic, J. M. Feedback stabilization of optically levitated particles. Appl. Phys. Lett. 30, 202–204 (1977)

    ADS  Article  Google Scholar 

  8. Morrow, N. V., Dutta, S. K. & Raithel, G. Feedback control of atomic motion in an optical lattice. Phys. Rev. Lett. 88, 093003 (2002)

    ADS  CAS  Article  Google Scholar 

  9. Fischer, T., Maunz, P., Pinkse, P. W. H., Puppe, T. & Rempe, G. Feedback on the motion of a single atom in an optical cavity. Phys. Rev. Lett. 88, 163002 (2002)

    ADS  CAS  Article  Google Scholar 

  10. Lynn, T. W., Birnbaum, K. & Kimble, H. J. Strategies for real-time position control of a single atom in cavity QED. J. Opt. B 7, 215–225 (2005)

    ADS  Article  Google Scholar 

  11. Bushev, P. et al. Feedback cooling of a single trapped ion. Phys. Rev. Lett. 96, 043003 (2006)

    ADS  Article  Google Scholar 

  12. Steck, D. A., Jacobs, K., Mabuchi, H., Habib, S. & Bhattacharya, T. Feedback cooling of atomic motion in cavity QED. Phys. Rev. A 74, 012322 (2006)

    ADS  Article  Google Scholar 

  13. Pinkse, P. W. H., Fischer, T., Maunz, P. & Rempe, G. Trapping an atom with single photons. Nature 404, 365–368 (2000)

    ADS  CAS  Article  Google Scholar 

  14. Hood, C. J., Lynn, T. W., Doherty, A. C., Parkins, A. S. & Kimble, H. J. The atom–cavity microscope: single atoms bound in orbit by single photons. Science 287, 1447–1453 (2000)

    ADS  CAS  Article  Google Scholar 

  15. Molmer, K., Castin, Y. & Dalibard, J. Monte Carlo wave-function method in quantum optics. J. Opt. Soc. Am. B 10, 524–538 (1993)

    ADS  Article  Google Scholar 

  16. Carmichael, H. ed. An Open Systems Approach to Quantum Optics (Springer, 1993)

    Book  Google Scholar 

  17. Puppe, T. et al. Trapping and observing single atoms in a blue-detuned intracavity dipole trap. Phys. Rev. Lett. 99, 013002 (2007)

    ADS  CAS  Article  Google Scholar 

  18. Maunz, P. et al. Cavity cooling of a single atom. Nature 428, 50–52 (2004)

    ADS  CAS  Article  Google Scholar 

  19. Khudaverdyan, M. et al. Quantum jumps and spin dynamics of interacting atoms in a strongly coupled atom–cavity system. Phys. Rev. Lett. 103, 123006 (2009)

    ADS  CAS  Article  Google Scholar 

  20. Kubanek, A. et al. Two-photon gateway in one-atom cavity quantum electrodynamics. Phys. Rev. Lett. 101, 203602 (2008)

    ADS  CAS  Article  Google Scholar 

  21. Braginsky, V. B. & Khalili, F. Y. eds. Quantum Measurement (Cambridge Univ. Press, 1992)

    Book  Google Scholar 

Download references

Acknowledgements

Partial support by the Bavarian PhD programme of excellence QCCC, the Deutsche Forschungsgemeinschaft research unit 635 and the European Union project SCALA are gratefully acknowledged.

Author Contributions All authors contributed to the design and implementation of the experiment, the interpretation of the results and the writing of the manuscript.

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Authors and Affiliations

  1. Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany ,

    A. Kubanek, M. Koch, C. Sames, A. Ourjoumtsev, P. W. H. Pinkse, K. Murr & G. Rempe

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  1. A. Kubanek
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  2. M. Koch
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  3. C. Sames
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  4. A. Ourjoumtsev
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  5. P. W. H. Pinkse
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  6. K. Murr
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  7. G. Rempe
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Correspondence to A. Kubanek or G. Rempe.

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Kubanek, A., Koch, M., Sames, C. et al. Photon-by-photon feedback control of a single-atom trajectory. Nature 462, 898–901 (2009). https://doi.org/10.1038/nature08563

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