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Observation of quantum-measurement backaction with an ultracold atomic gas

Abstract

Current research on micromechanical resonators strives for quantum-limited detection of the motion of macroscopic objects. Prerequisite to this goal is the observation of measurement backaction consistent with quantum metrology limits. However, thermal noise currently dominates measurements and precludes ground-state preparation of the resonator. Here, we establish the collective motion of an ultracold atomic gas confined tightly within a Fabry–Perot optical cavity as a system for investigating the quantum mechanics of macroscopic bodies. The cavity-mode structure selects a particular collective vibrational motion that is measured by the cavity’s optical properties, actuated by the cavity optical field and subject to backaction by the quantum force fluctuations of this field. Experimentally, we quantify such fluctuations by measuring the cavity-light-induced heating of the intracavity atomic ensemble. These measurements represent the first observation of backaction on a macroscopic mechanical resonator at the standard quantum limit.

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Figure 1: Experimental schematic diagram.
Figure 2: Cavity-based observation of evaporative atomic losses due to cavity-light-induced diffusive heating.
Figure 3: Cavity heating of the collective atomic motion in a strongly coupled Fabry–Perot cavity over spontaneous emission dominated free-space heating.

References

  1. Kleckner, D. & Bouwmeester, D. Sub-kelvin optical cooling of a micromechanical resonator. Nature 444, 75–78 (2006).

    Article  ADS  Google Scholar 

  2. Poggio, M. et al. Feedback cooling of a cantilever’s fundamental mode below 5 mK. Phys. Rev. Lett. 99, 017201 (2007).

    Article  ADS  Google Scholar 

  3. Arcizet, O. et al. Radiation-pressure cooling and optomechanical instability of a micromirror. Nature 444, 71–74 (2006).

    Article  ADS  Google Scholar 

  4. Gigan, S. et al. Self-cooling of a micromirror by radiation pressure. Nature 444, 67–70 (2006).

    Article  ADS  Google Scholar 

  5. Naik, A. et al. Cooling a nanomechanical resonator with quantum back-action. Nature 443, 193–196 (2006).

    Article  ADS  Google Scholar 

  6. Thompson, J. D. et al. Strong dispersive coupling of a high-finesse cavity to a micromechanical membrane. Nature 452, 72–75 (2008).

    Article  ADS  Google Scholar 

  7. Schliesser, A. et al. Radiation pressure cooling of a micromechanical oscillator using dynamical backaction. Phys. Rev. Lett. 97, 243905 (2006).

    Article  ADS  Google Scholar 

  8. Huang, X. M. H. et al. Nanodevice motion at microwave frequencies. Nature 421, 496 (2003).

    Article  ADS  Google Scholar 

  9. Horak, P. et al. Cavity-induced atom cooling in the strong coupling regime. Phys. Rev. Lett. 79, 4974–4977 (1997).

    Article  ADS  Google Scholar 

  10. Vuletić, V. & Chu, S. Laser cooling of atoms, ions or molecules by coherent scattering. Phys. Rev. Lett. 84, 3787–3790 (2000).

    Article  ADS  Google Scholar 

  11. Marquardt, F. et al. Quantum theory of cavity-assisted sideband cooling of mechanical motion. Phys. Rev. Lett. 99, 093902 (2007).

    Article  ADS  Google Scholar 

  12. Vitali, D. et al. Macroscopic mechanical oscillators at the quantum limit through optomechanical cooling. J. Opt. Soc. Am. B 20, 1054–1065 (2003).

    Article  ADS  Google Scholar 

  13. Wilson-Rae, I. et al. Theory of ground state cooling of a mechanical oscillator using dynamical backaction. Phys. Rev. Lett. 99, 093901 (2007).

    Article  ADS  Google Scholar 

  14. Bouchoule, I. et al. Neutral atoms prepared in Fock states of a one-dimensional harmonic potential. Phys. Rev. A 59, R8–R11 (1999).

    Article  ADS  Google Scholar 

  15. Harber, D. et al. Measurement of the Casimir-Polder force through center-of-mass oscillations of a Bose–Einstein condensate. Phys. Rev. A 72, 033610 (2005).

    Article  ADS  Google Scholar 

  16. Mohideen, U. & Roy, A. Precision measurement of the Casimir force from 0.1 to 0.9 μm. Phys. Rev. Lett. 81, 4549–4552 (1998).

    Article  ADS  Google Scholar 

  17. Hood, C. et al. The atom-cavity microscope: single atoms bound in orbit by single photons. Science 287, 1447–1453 (2000).

    Article  ADS  Google Scholar 

  18. Mabuchi, H. et al. Real-time detection of individual atoms falling through a high-finesse optical cavity. Opt. Lett. 21, 1393–1395 (1996).

    Article  ADS  Google Scholar 

  19. Brennecke, F. et al. Cavity QED with a Bose–Einstein condensate. Nature 450, 268–271 (2007).

    Article  ADS  Google Scholar 

  20. Colombe, Y. et al. Strong atom-field coupling for Bose–Einstein condensates in an optical cavity on a chip. Nature 450, 272–276 (2007).

    Article  ADS  Google Scholar 

  21. Gupta, S. et al. Cavity nonlinear optics at low photon numbers from collective atomic motion. Phys. Rev. Lett. 99, 213601 (2007).

    Article  ADS  Google Scholar 

  22. Dorsel, A. et al. Optical bistability and mirror confinement induced by radiation pressure. Phys. Rev. Lett. 51, 1550–1553 (1983).

    Article  ADS  Google Scholar 

  23. Caves, C. M. Quantum-mechanical noise in an interferometer. Phys. Rev. D 23, 1693–1708 (1981).

    Article  ADS  Google Scholar 

  24. Marquardt, F., Harris, J. G. E. & Girvin, S. M. Dynamical multistability induced by radiation pressure in high-finesse micromechanical optical cavities. Phys. Rev. Lett. 96, 103901 (2006).

    Article  ADS  Google Scholar 

  25. Dalibard, J. & Cohen-Tannoudji, C. Dressed-atom approach to atomic motion in laser light: The dipole force revisited. J. Opt. Sci. Am. B 2, 1707–1720 (1985).

    Article  ADS  Google Scholar 

  26. Gordon, J. P. & Ashkin, A. Motion of atoms in a radiation trap. Phys. Rev. A 21, 1606–1617 (1980).

    Article  ADS  Google Scholar 

  27. Maunz, P. et al. Normal-mode spectroscopy of a single-bound-atom–cavity system. Phys. Rev. Lett. 94, 033002 (2005).

    Article  ADS  Google Scholar 

  28. Münstermann, P. et al. Dynamics of single-atom motion observed in a high-finesse cavity. Phys. Rev. Lett. 82, 3791–3794 (1999).

    Article  ADS  Google Scholar 

  29. Loudon, R. & Knight, P. Squeezed light. J. Mod. Opt. 34, 709–795 (1987).

    Article  MathSciNet  ADS  Google Scholar 

  30. Kuzmich, A., Bigelow, N. P. & Mandel, L. Atomic quantum non-demolition measurements and squeezing. Europhys. Lett. 42, 481–486 (1998).

    Article  ADS  Google Scholar 

  31. Takahashi, Y. et al. Quantum nondemolition measurement of spin via the paramagnetic Faraday rotation. Phys. Rev. A 60, 4974–4979 (1999).

    Article  ADS  Google Scholar 

  32. Bouchoule, I. & Mølmer, K. Preparation of spin-squeezed atomic states by optical-phase-shift measurement. Phys. Rev. A 66, 043811 (2002).

    Article  ADS  Google Scholar 

  33. Auzinsh, M. et al. Can a quantum nondemolition measurement improve the sensitivity of an atomic magnetometer? Phys. Rev. Lett. 93, 173002 (2004).

    Article  ADS  Google Scholar 

  34. Hald, J. et al. Spin squeezed atoms: a macroscopic entangled ensemble created by light. Phys. Rev. Lett. 83, 1319–1322 (2000).

    Article  ADS  Google Scholar 

  35. Geremia, J. & Mabuchi, J. K. S. Real-time quantum feedback control of atomic spin-squeezing. Science 304, 270–273 (2004).

    Article  ADS  Google Scholar 

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Acknowledgements

We thank T. Purdy and S. Schmid for early contributions to the experimental apparatus, and S. M. Girvin, J. Harris, H. J. Kimble, H. Mabuchi and M. Raymer for helpful discussions. This work was supported by AFOSR, DARPA and the David and Lucile Packard Foundation.

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K.W.M., K.L.M. and S.G. contributed experimental work, data analysis and theoretical work to the article and supplemental information. D.M.S.-K. contributed project guidance, data analysis and theoretical work.

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Correspondence to Dan M. Stamper-Kurn.

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Supplementary Information

Supplementary Information and Supplementary Figure 1 (PDF 819 kb)

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Murch, K., Moore, K., Gupta, S. et al. Observation of quantum-measurement backaction with an ultracold atomic gas. Nature Phys 4, 561–564 (2008). https://doi.org/10.1038/nphys965

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