Origin of quantum-mechanical complementarity without momentum back action in atom-interferometry experiments - art. no. 015601

We identify the physical origin of the loss of interference pattern in the which-path atom-interferometery experiments that have been discussed widely . The origin of complementarity between the which-path information and the interference pattern is a discrete spinor phase with random sign. This clar ifies how complementarity can arise without the Heisenbeg back action in mo mentum.