Letter | Published:

Light speed reduction to 17 metres per second in an ultracold atomic gas

Nature volume 397, pages 594598 (18 February 1999) | Download Citation

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Abstract

Techniques that use quantum interference effects are being actively investigated to manipulate the optical properties of quantum systems1. One such example is electromagnetically induced transparency, a quantum effect that permits the propagation of light pulses through an otherwise opaque medium2,3,4,5. Here we report an experimental demonstration of electromagnetically induced transparency in an ultracold gas of sodium atoms, in which the optical pulses propagate at twenty million times slower than the speed of light in a vacuum. The gas is cooled to nanokelvin temperatures by laser and evaporative cooling6,7,8,9,10. The quantum interference controlling the optical properties of the medium is set up by a ‘coupling’ laser beam propagating at a right angle to the pulsed ‘probe’ beam. At nanokelvin temperatures, the variation of refractive index with probe frequency can be made very steep. In conjunction with the high atomic density, this results in the exceptionally low light speeds observed. By cooling the cloud below the transition temperature for Bose–Einstein condensation11,12,13 (causing a macroscopic population of alkali atoms in the quantum ground state of the confining potential), we observe even lower pulse propagation velocities (17 m s−1) owing to the increased atom density. We report an inferred nonlinear refractive index of 0.18 cm2 W−1 and find that the system shows exceptionally large optical nonlinearities, which are of potential fundamental and technological interest for quantum optics.

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References

  1. 1.

    , & (eds) Highlights in quantum optics. Phil. Trans. R. Soc. Lond. A 355, 2215–2416 (1997).

  2. 2.

    Electromagnetically induced transparency. Phys. Today 50(7), 36–42 (1997).

  3. 3.

    & Quantum Optics (Cambridge Univ. Press, (1997)).

  4. 4.

    in Progress in Optics (ed. Wolf, E.) 257–354 (Elsevier Science, Amsterdam, (1996)).

  5. 5.

    , & Coherent population transfer among quantum states of atoms and molecules. Rev. Mod. Phys. 70, 1003–1006 (1998).

  6. 6.

    The manipulation of neutral particles. Rev. Mod. Phys. 70, 685–706 (1998).

  7. 7.

    Manipulating atoms with photons. Rev. Mod. Phys. 70 , 707–719 (1998).

  8. 8.

    Laser cooling and trapping of neutral atoms. Rev. Mod. Phys. 70, 721–741 (1998).

  9. 9.

    Evaporative cooling of magnetically trapped and compressed spin-polarized hydrogen. Phys. Rev. B 34, 3476– 3479 (1986).

  10. 10.

    et al. Evaporative cooling of spin-polarized atomic hydrogen. Phys. Rev. Lett. 61, 935–938 (1988).

  11. 11.

    , , , & Observation of Bose-Einstein condensation in a dilute atomic vapor. Science 269, 198–201 (1995).

  12. 12.

    et al. Bose-Einstein condensation in a gas of sodium atoms. Phys. Rev. Lett. 75, 3969–3973 (1995).

  13. 13.

    , & Bose-Einstein condensation of lithium: observation of limited condensate number. Phys. Rev. Lett. 78, 985–989 (1997).

  14. 14.

    et al. Near-resonant spatial images of confined Bose-Einstein condensates in a 4-Dee magnetic bottle. Phys. Rev. A 58, R54– R57 (1998).

  15. 15.

    , & Anew atomic beam source: The “candlestick”. Rev. Sci. Instrum. 65, 3746– 3750 (1994).

  16. 16.

    , & Dispersive properties of electromagnetically induced transparency. Phys. Rev. A 46, R29– R32 (1992).

  17. 17.

    , & Formation of shape-preserving pulses in a nonlinear adiabatically integrable system. Phys. Rev. Lett. 73 , 3183–3186 (1994).

  18. 18.

    , , & Measurement of dispersive properties of electromagnetically induced transparency in rubidium atoms. Phys. Rev. Lett. 74, 666– 669 (1995).

  19. 19.

    , , & Electromagnetically induced transparency: propagation dynamics. Phys. Rev. Lett. 74, 2447–2450 (1995).

  20. 20.

    & Giant Kerr nonlinearities obtained by electromagnetically induced transparency. Opt. Lett. 21, 1936–1938 (1996).

  21. 21.

    , , & Cold atoms: A new medium for quantum optics. Appl. Phys. B 60, 129–134 (1995).

  22. 22.

    , , & Measurements of relative phase in two-component Bose-Einstein condensates. Phys. Rev. Lett. 81, 1543– 1546 (1998).

  23. 23.

    & Coherent population trapping of Bose-Einstein condensates: detection of phase diffusion. Eur. Phys. J. D (submitted).

  24. 24.

    & Photon switching by quantum interference. Phys. Rev. Lett. 81, 3611– 3614 (1998).

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Acknowledgements

We thank J. A. Golovchenko for discussions and C. Liu for experimental assistance. L.V.H. acknowledges support from the Rowland Institute for Science. S.E.H. is supported by the US Air Force Office of Scientific Research, the US Army Research Office, and the US Office of Naval Research. C.H.B. is supported by an NSF fellowship.

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Affiliations

  1. *Rowland Institute for Science, 100 Edwin H. Land Boulevard, Cambridge, Massachusetts 02142, USA

    • Lene Vestergaard Hau
    • , Zachary Dutton
    •  & Cyrus H. Behroozi
  2. †Department of Physics, Division of Engineering, Harvard University, Cambridge, Massachusetts 02138, USA

    • Lene Vestergaard Hau
    •  & Zachary Dutton
  3. ‡Applied Sciences, Harvard University , Cambridge, Massachusetts 02138, USA

    • S. E. Harris
  4. §Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA

    • Cyrus H. Behroozi

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Correspondence to Lene Vestergaard Hau.

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https://doi.org/10.1038/17561

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