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Applied Physics B

, Volume 72, Issue 1, pp 91–99 | Cite as

Multiple-beam Ramsey interference and quantum decoherence

  • M. Mei
  • M. Weitz
Article

Abstract.

We study the effect of photon scattering from a path of a four-beam atomic interference setup, which is based on a cesium atomic beam and two subsequent optical Ramsey pulses projecting the atoms onto a multilevel dark state. While in two-beam interference, any attempt to keep track of an interfering path reduces the fringe contrast, we demonstrate that photon scattering in a multiple-path arrangement cannot only lead to a decrease, but - under certain conditions - also to an increase of the interference contrast. The results are confirmed by a density-matrix calculation. We are aware that in all cases the “which-path” information carried away by the scattered photons leads to a loss of information that is contained in the atomic quantum state. An approach to quantify this “which-path” information using observed fringe signals is presented; it allows for an appropriate measure of quantum decoherence in multiple-path interference.

PACS: 03.65.-w; 03.75.Dg; 32.80.-t 

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Copyright information

© Springer-Verlag 2000

Authors and Affiliations

  • M. Mei
    • 1
  • M. Weitz
    • 1
  1. 1.Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, GermanyDE

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