When an observer wants to identify a quantum state, which is known to be one of a given set of nonorthogonal states, the act of observation causes a disturbance to that state. We investigate the trade-off between the information gain and that disturbance. This issue has important applications in quantum cryptography. The optimal detection method, for a given tolerated disturbance, is explicitly found in the case of two equiprobable nonorthogonal pure states.
Physical Review A
- Pub Date:
- April 1996
- Quantum Physics
- 20 pages, standard LaTeX, four png figures (also available from the authors: firstname.lastname@example.org and email@example.com)