SQUIDs, Brains and Gravity Waves

MAR 01, 1986

Superconducting quantum interference devices are so sensitive to magnetic flux that they can map the tiny magnetic fields emanating from the human brain and detect the submicroscopic motions of gravity‐wave detectors.

DOI: 10.1063/1.881054

John Clarke

▸ A lonely instrument in Baja California records tiny fluctuations in the Earth’s magnetic field, giving valuable information on the location of geothermal energy.

▸ An extremely quiet amplifier detects electrical noise generated by the fluctuating spins in a collection of chlorine nuclei—the first observation of nuclear‐spin noise.

▸ Superconducting gradiometers in liquid helium measure tiny fluctuating magnetic fields emanating from the human brain (see figure 1), pinpointing the source of the electrical discharge associated with focal epilepsy.

▸ An aluminum bar weighing 4800 kg and cooled to 4.2 K rests in a vacuum chamber at Stanford University, working as the world’s most sensitive monitor of gravitational radiation.

References

1. For a review of geophysical applications, see J. Clarke, IEEE Trans. Magn. MAG‐19, 288 (1983).https://doi.org/IEMGAQ
2. T. Sleator, E. L. Hahn, C. Hilbert, J. Clarke, Phys. Rev. Lett. 55, 1742 (1985)https://doi.org/PRLTAO
3. D. S. Barth, W. Sutherling, J. EngelJr., J. Beatty, Science 223, 293 (1984).https://doi.org/SCIEAS
4. M. Bassan, W. M. Fairbank, E. Mapoles, M. S. McAshan, P. F. Michelson, B. Moskowitz, K. Ralls, R. C. Taber, in Proc. 3rd Marcel Grossmann Meeting on General Relativity, H. Ning, ed., North Holland, New York (1983), p. 667.
5. J. E. Zimmerman, P. Thiene, J. T. Harding, J. Appl. Phys. 41, 1572 (1970).https://doi.org/JAPIAU
6. See, for example, M. Tinkham, Introduction to Superconductivity, McGraw‐Hill, New York (1975).
7. For a detailed description of SQUIDS and copious references, see: J. Clarke, in Superconductor Applications: SQUIDS and Machines, B. B. Schwartz, S. Foner, eds., Plenum, New York (1977) p. 67;
J. Clarke, IEEE Trans. Electron Devices ED‐27, 1896 (1980); https://doi.org/IETDAI
J. Clarke, in Advances in Superconductivity, B. Deaver, J. Ruvalds, eds., Plenum, New York (1983) p. 13.
8. For collections of papers on SQUIDS, see the proceedings of the applied‐superconductivity conferences. The last three proceedings are in IEEE Trans. Magn. MAG‐17, no. 1 (1981); https://doi.org/IEMGAQ
MAG‐19, no. 3 (1983); https://doi.org/IEMGAQ , IEEE Trans. Magn.
MAG‐21, no. 2 (1985). https://doi.org/IEMGAQ , IEEE Trans. Magn.
Also see the Proc. Int. Conf. on Superconducting Quantum Interference Devices and Their Applications, H. D. Hahlbohm, H. Lübbig, eds., Walter de Gruyter, Berlin (1977), (1980), (1985).
9. J. C. Jaklevic, J. Lambe, A. H. Silver, J. E. Mercereau, Phys. Rev. Lett. 12, 159 (1964).https://doi.org/PRLTAO
10. See IBM J. Res. Dev. 24, no. 2 (March 1980).https://doi.org/IBMJAE
11. C. T. Rogers, R. A. Buhrman, Phys. Rev. Lett. 53, 1272 (1984); https://doi.org/PRLTAO
R. H. Koch, in Noise in Physical Systems, M. Savelli, G. Leroy, J. P. Nougier, eds., North Holland, New York (1983) p. 377.
12. C. D. Tesche, K. H. Brown, A. C. Callegari, M. M. Chen, J. H. Greiner, H. C. Jones, M. B. Ketchen, K. K. Kim, A. W. Kleinsasser, H. A. Notarys, G. Proto, R. H. Wang, T. Yogi, Proc. 17th Int. Conf. on Low Temperature Physics, U. Eckern, A. Schmid, W. Weber, H. Wuhl, eds., North Holland, New York (1984), p. 263.
13. G. J. van Nieuwenhuyzen, V. J. de Waal, Appl. Phys. Lett. 46, 439 (1985).https://doi.org/APPLAB
14. J. E. Zimmerman, in Superconducting Quantum Interference Devices and Their Applications, H. D. Hahlbohm, H. Lübbig, eds., Walter de Gruyter, Berlin (1980), p. 423;
W. A. Little, Rev. Sci. Instrum. 55, 661 (1984).https://doi.org/RSINAK
15. For extensive reviews, see S. J. Williamson, L. Kaufman, J. Magn. Magn. Mater. 22, 129 (1981); https://doi.org/JMMMDC
S. J. Williamson, G. L. Romani, L. Kaufman, I. Modena, eds., Biomagnetism: An Interdisciplinary Approach, Plenum, New York (1983).
16. For an elementary review on gravity waves, see S. L. Shapiro, R. F. Stark, S. J. Teukolsky, Am. Sci. 73, 248 (1985).https://doi.org/AMSCAC
17. G. L. Romani, S. J. Williamson, L. Kaufman, Science 216, 1339 (1982).https://doi.org/SCIEAS
18. R. P. Giffard, Phys. Rev. A 14, 2478 (1976).https://doi.org/PLRAAN
19. For a review, see C. M. Caves, K. S. Thorne, R. W. P. Drever, V. D. Sandberg, M. Zimmermann, Rev. Mod. Phys. 52, 341 (1980).https://doi.org/RMPHAT

More about the Authors

John Clarke. University of California, Berkeley.