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A subfemtotesla multichannel atomic magnetometer

Abstract

The magnetic field is one of the most fundamental and ubiquitous physical observables, carrying information about all electromagnetic phenomena. For the past 30 years, superconducting quantum interference devices (SQUIDs) operating at 4 K have been unchallenged as ultrahigh-sensitivity magnetic field detectors1, with a sensitivity reaching down to 1 fT Hz-1/2 (1 fT = 10-15 T). They have enabled, for example, mapping of the magnetic fields produced by the brain, and localization of the underlying electrical activity (magnetoencephalography). Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have approached similar levels of sensitivity using large measurement volumes2,3, but have much lower sensitivity in the more compact designs required for magnetic imaging applications4. Higher sensitivity and spatial resolution combined with non-cryogenic operation of atomic magnetometers would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain. Here we describe a new spin-exchange relaxation-free (SERF) atomic magnetometer, and demonstrate magnetic field sensitivity of 0.54 fT Hz-1/2 with a measurement volume of only 0.3 cm3. Theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01 fT Hz-1/2. We also demonstrate simple multichannel operation of the magnetometer, and localization of magnetic field sources with a resolution of 2 mm.

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Figure 1: Relaxation rate and theoretical magnetic field sensitivity.
Figure 2: Experimental set-up.
Figure 3: Magnetic field sensitivity and bandwidth of the magnetometer.
Figure 4: Magnetic gradient imaging.

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References

  1. Weinstock, H. (ed.) SQUID Sensors: Fundamentals, Fabrication and Applications (Kluwer Academic, Dordrecht, 1996)

  2. Aleksandrov, E. B. et al. Laser pumping in the scheme of an Mx-magnetometer. Optics Spectrosc. 78, 292–298 (1995)

    ADS  Google Scholar 

  3. Budker, D., Kimball, D. F., Rochester, S. M., Yashchuk, V. V. & Zolotorev, M. Sensitive magnetometry based on non-linear magneto-optical rotation. Phys. Rev. A 62, 043403 (2000)

    Article  ADS  Google Scholar 

  4. Affolderbach, C., Stähler, M., Knappe, S. & Wynands, R. An all-optical, high sensitivity magnetic gradiometer. Appl. Phys. B 75, 605–612 (2002)

    Article  ADS  CAS  Google Scholar 

  5. Tsuei, C. C. & Kirtley, J. R. Phase-sensitive evidence for d-wave pairing symmetry in electron-doped cuprate superconductors. Phys. Rev. Lett. 85, 182–185 (2000)

    Article  ADS  CAS  Google Scholar 

  6. Harry, G. M., Jin, I., Paik, H. J., Stevenson, T. R. & Wellstood, F. C. Two-stage superconducting-quantum-interference-device amplifier in a high-Q gravitational wave transducer. Appl. Phys. Lett. 76, 1446–1448 (2000)

    Article  ADS  CAS  Google Scholar 

  7. Greenberg, Ya. S. Application of superconducting quantum interference devices to nuclear magnetic resonance. Rev. Mod. Phys. 70, 175–222 (1998)

    Article  ADS  CAS  Google Scholar 

  8. McDermott, R. et al. Liquid-state NMR and scalar couplings in microtesla magnetic fields. Science 295, 2247–2249 (2002)

    Article  ADS  CAS  Google Scholar 

  9. Kirschvink, J. L., Maine, A. T. & Vali, H. Paleomagnetic evidence of a low-temperature origin of carbonate in the Martian meteorite ALH84001. Science 275, 1629–1633 (1997)

    Article  ADS  CAS  Google Scholar 

  10. Tralshawala, N., Claycomb, J. R. & Miller, J. H. Practical SQUID instrument for non-destructive testing. Appl. Phys. Lett. 71, 1573–1575 (1997)

    Article  ADS  CAS  Google Scholar 

  11. Clem, T. R. Superconducting magnetic gradiometers for underwater target detection. Naval Engineers J. 110, 139–149 (1998)

    Article  Google Scholar 

  12. Hämäläinen, M. et al. Magnetoencephalography—theory, instrumentation, and applications to non-invasive studies of the working human brain. Rev. Mod. Phys. 65, 413–497 (1993)

    Article  ADS  Google Scholar 

  13. Rodriguez, E. et al. Perception's shadow: long-distance synchronization of human brain activity. Nature 397, 430–433 (1999)

    Article  ADS  CAS  Google Scholar 

  14. Zimmerman, J. E., Thiene, P. & Harding, J. T. Design and operation of stable RF-biased superconducting point-contact quantum devices, and a note on properties of perfectly clean metal contacts. J. Appl. Phys. 41, 1572–1580 (1970)

    Article  ADS  Google Scholar 

  15. Drung, D., Bechstein, S., Franke, K. P., Scheiner, M. & Schurig, T. Improved direct-coupled dc SQUID read-out electronics with automatic bias voltage tuning. IEEE Trans. Appl. Supercond. 11, 880–883 (2001)

    Article  ADS  Google Scholar 

  16. Oukhanski, N., Stolz, R., Zakosarenko, V. & Meyer, H. G. Low-drift broadband directly coupled dc SQUID read-out electronics. Physica C 368, 166–170 (2002)

    Article  ADS  CAS  Google Scholar 

  17. Del Gratta, C., Pizzella, V., Tecchio, F. & Romani, G. L. Magnetoencephalography—a noninvasive brain imaging method with 1 ms time resolution. Rep. Prog. Phys. 64, 1759–1814 (2001)

    Article  ADS  Google Scholar 

  18. Nenonen, J., Montonen, J. & Katila, T. Thermal noise in biomagnetic measurements. Rev. Sci. Instrum. 67, 2397–2405 (1996)

    Article  ADS  CAS  Google Scholar 

  19. Dupont-Roc, J., Haroche, S., Cohen-Tannoudji, C. Detection of very weak magnetic fields (10-9 gauss) by 87Rb zero-field level crossing resonances. Phys. Lett. A 28, 638–639 (1969)

    Article  ADS  CAS  Google Scholar 

  20. Budker, D. et al. Resonant nonlinear magneto-optical effects in atoms. Rev. Mod. Phys. 74, 1153–1201 (2002)

    Article  ADS  CAS  Google Scholar 

  21. Allred, J. C., Lyman, R. N., Kornack, T. W. & Romalis, M. V. High-sensitivity atomic magnetometer unaffected by spin-exchange relaxation. Phys. Rev. Lett. 89, 130801 (2002)

    Article  ADS  CAS  Google Scholar 

  22. Budker, D., Yashchuk, V. & Zolotorev, M. Nonlinear magneto-optic effects with ultra-narrow widths. Phys. Rev. Lett. 81, 5788–5791 (1998)

    Article  ADS  CAS  Google Scholar 

  23. Alexandrov, E. B., Balabas, M. V., Pasgalev, A. S., Vershovskii, A. K. & Yakobson, N. N. Double-resonance atomic magnetometers: From gas discharge to laser pumping. Laser Phys. 6, 244–251 (1996)

    CAS  Google Scholar 

  24. Kandori, A., Miyashita, T. & Tsukada, K. Cancellation technique of external noise inside a magnetically shielded room used for biomagnetic measurements. Rev. Sci. Instrum. 71, 2184–2190 (2000)

    Article  ADS  CAS  Google Scholar 

  25. Varpula, T. & Poutanen, T. Magnetic field fluctuations arising from thermal motion of electric charge in conductors. J. Appl. Phys. 55, 4015–4021 (1984)

    Article  ADS  Google Scholar 

  26. Ts'o, D. Y., Frostig, R. D., Lieke, E. E. & Grinvald, A. Functional organisation of primate visual cortex revealed by high-resolution optical imaging. Science 249, 417–420 (1990)

    Article  ADS  CAS  Google Scholar 

  27. Happer, W. & Tam, A. C. Effect of rapid spin exchange on the magnetic-resonance spectrum of alkali vapors. Phys. Rev. A 16, 1877–1991 (1977)

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

This work was supported by the NIH, the Packard Foundation and Princeton University.

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Correspondence to M. V. Romalis.

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Kominis, I., Kornack, T., Allred, J. et al. A subfemtotesla multichannel atomic magnetometer. Nature 422, 596–599 (2003). https://doi.org/10.1038/nature01484

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