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.

• Received 16 October 1997

DOI:https://doi.org/10.1103/PhysRevA.58.3477