A suitable generalized measurement described by a 4-element positive
operator-valued measure (POVM) on each particle of a two-qubit system in the
singlet state is, from the point of view of Einstein, Podolsky, and Rosen's
(EPR's) criterion of elements of reality, equivalent to a random selection
between two alternative projective measurements. It is shown that an
EPR-experiment with a fixed POVM on each particle provides a violation of
Bell's inequality without requiring local observers to choose between the
alternatives. This approach could be useful for designing a loophole-free test
of Bell's inequality.Comment: LaTeX, 13 pages, 3 figure
