In an analysis of the Afshar experiment R.E. Kastner points out that the selection system used in this experiment randomly separates the photons that go to the detectors, and therefore no which-way information is obtained. In this paper we present a modified but equivalent version of the Afshar experiment that does not contain a selection device. The double-slit is replaced by two separate coherent laser beams that overlap under a small angle. At the intersection of the beams an interference pattern can be inferred in a non-perturbative manner, which confirms the existence of a superposition state. In the far field the beams separate without the use of a lens system. Momentum conservation warranties that which-way information is preserved. We also propose an alternative sequence of Stern-Gerlach devices that represents a close analogue to the Afshar experimental set up.

Date Published: 31 August 2007
PDF: 8 pages
Proc. SPIE 6664, The Nature of Light: What Are Photons?, 66640O (31 August 2007); doi: 10.1117/12.730965

Published in SPIE Proceedings Vol. 6664:
The Nature of Light: What Are Photons?
Chandrasekhar Roychoudhuri; Al F. Kracklauer; Katherine Creath, Editor(s)