Disturbance by optimal discrimination

Ryuitiro Kawakubo, Tatsuhiko Koike

Published 2017-11-21Version 1

We show that any optimal unambiguous discrimination changes distinguishable states indistinguishable when the inconclusive outcome is obtained, which was proved under restricted conditions by Chefles [Phys. Lett. A 239, 339 (1998)]. Our proof is based on a simple observation which makes it easy and removes its restrictions. The method may have a wide variety of applications in contexts other than state discrimination.