We extend the concept of the relative error to mixed-state cloning and related physical operations, in which the ancilla contains some information a priori about the input state. The lower bound on the relative error is obtained. It is shown that this result provides further support for a stronger no-cloning theorem.
Journal of Optics B: Quantum and Semiclassical Optics
- Pub Date:
- December 2003
- Mixed-state cloningrelative error of state-dependent cloningstronger no-cloning theorem;
- Quantum Physics
- 5 pages, ReVTeX, no figures. The main result is completed. The bibliography is extended and corrected. More explanations