  A setup based on the Franson optical interferometer is analyzed, which allows
us to detect the coherence properties of Cooper pairs emerging via tunneling
from a superconductor in contact with two one-dimensional channels. By tuning
the system parameters we show that both the internal coherence of the emitted
Cooper pairs, which is proportional to Pippard's length, and the de Broglie
wavelength of their center-of-mass motion can be measured via current-current
correlation measurements.
