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.
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Received: 27 July 2000 / Published online: 6 December 2000
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Mei, M., Weitz, M. Multiple-beam Ramsey interference and quantum decoherence . Appl Phys B 72, 91–99 (2001). https://doi.org/10.1007/s003400000482
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DOI: https://doi.org/10.1007/s003400000482