Complementarity and quantum erasure inwelcher Wegexperiments

Abstract
We extend the concept of distinguishability and likelihood introduced by Englert in Phys. Rev. Lett. 77, 2154 (1996) to encompass quantum erasure. We delineate the necessary and sufficient condition for obtaining optimal values of distinguishability and erasure. Finally we apply these measures on a gedanken welcher Weg experiment consisting of a coupled atom-photon interferometer.