Is spin coherence like Humpty-Dumpty? I. Simplified treatment

Berthold-Georg Englert; Julian Schwinger; Marlan O. Scully

doi:10.1007/BF01909939

Foundations of Physics

October 1988, Volume 18, Issue 10, pp 1045–1056

Is spin coherence like Humpty-Dumpty? I. Simplified treatment

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Berthold-Georg Englert
Julian Schwinger
Marlan O. Scully

Part IV. Invited Papers Dedicated To David Bohm

Received:: 20 January 1988

DOI: 10.1007/BF01909939

Cite this article as:: Englert, BG., Schwinger, J. & Scully, M.O. Found Phys (1988) 18: 1045. doi:10.1007/BF01909939

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Abstract

When Humpty-Dumpty had his great fall nobody could put him together again. A vastly more moderate challenge is to reunite the two partial beams of a Stern-Gerlach apparatus with such precision that the original spin state is recovered. Nevertheless, as we demonstrate, a substantial loss of spin coherence always occurs, unless the experimenter is able to control the magnetic field's inhomogeneity with an accuracy of at least one part in 10⁵.

References

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D. Bohm,Quantum Theory (Prentice-Hall, Englewood Cliffs, 1951).Google Scholar
2.
Ref. 1, pp. 604 and 605.Google Scholar
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The Oxford Dictionary of Nursery Rhymes, I. Opie and P. Opie, eds. (The Clarendon Press, Oxford, 1951), p. 213.Google Scholar
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W. Heisenberg,Die physikalischen Prinzipien der Quantentheorie (Hirzl, Leipzig, 1930), pp. 33 and 34.Google Scholar
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Other models of SGAs have been considered by M. O. Scully, R. Shea, and J. M. McCullen,Phys. Rep. 43, 487 (1978), as well as by M. O. Scully, W. E. Lamb, and A. Barut,Found. Phys. 17, 575 (1987).CrossRefGoogle Scholar
6.
The uncertainty δΦ of the accumulated Larmor precession angle must also be kept very small. This is more easily achieved for magnetic field configurations different from the one in Fig. 1. For details consult J. Schwinger, M. O. Scully, and B.-G. Englert, “Is Spin Coherence like Humpty-Dumpty? II. General Theory,” to appear in the Otto Stern Centennial Issue ofZ. Phys. D (1988).
7.
Incidentally, in the original experiment by W. Gerlach and O. Stern,Z. Phys. 8, 110 (1922), and9, 349 (1922), the deflection of the two partial beams showed a strong asymmetry.CrossRefGoogle Scholar

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Authors and Affiliations

Berthold-Georg Englert
- 1
Julian Schwinger
- 1
Marlan O. Scully
- 1
- 4

1.Center for Advanced Studies and Department of Physics and AstronomyUniversity of New MexicoAlbuquerque
2.Sektion PhysikUniversität MünchenGarchingFRG
3.Dept. of PhysicsUniv. of CaliforniaLos Angeles
4.Max-Planck Institut für QuantenoptikGarchingFRG

Is spin coherence like Humpty-Dumpty? I. Simplified treatment

Abstract

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