  Determination of the path taken by a quantum particle leads to a suppression
of interference and to a classical behavior. We employ here a quantum 'which
path' detector to perform accurate path determination in a
two-path-electron-interferometer; leading to full suppression of the
interference. Following the dephasing process we recover the interference by
measuring the cross-correlation between the interferometer and detector
currents. Under our measurement conditions every interfering electron is
dephased by approximately a single electron in the detector - leading to mutual
entanglement of approximately single pairs of electrons.
