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Nature 422, 596-599 (10 April 2003) | doi:10.1038/nature01484; Received 24 October 2002; Accepted 4 February 2003

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A subfemtotesla multichannel atomic magnetometer

I. K. Kominis1,2, T. W. Kornack1, J. C. Allred3 & M. V. Romalis1

  1. Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
  2. Department of Physics, University of Washington, Seattle, Washington 98195, USA
  3. Present address: Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

Correspondence to: M. V. Romalis1 Correspondence and requests for materials should be addressed to M.R. (e-mail: Email: romalis@princeton.edu).

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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.

  1. Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
  2. Department of Physics, University of Washington, Seattle, Washington 98195, USA
  3. Present address: Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

Correspondence to: M. V. Romalis1 Correspondence and requests for materials should be addressed to M.R. (e-mail: Email: romalis@princeton.edu).