Key points are not available for this paper at this time.
In a two-particle interferometer, one can study the variation of both single- and joint-detection probabilities as functions of the phase shifts of the beams. By combining the usual definition for one-particle fringe visibility v₈ (i=1, 2) with a reasonable proposed definition for two-particle fringe visibility v₁₂, we show that v₈^2+v₁₂^21 or, equivalently, v₈v₁₂1/2. Some extensions are discussed.
Jaeger et al. (Sun,) studied this question.