Unambiguous comparison of unitary channels
Quantum Physics
2009-01-09 v2
Abstract
We address the problem of unambiguous comparison of a pair of unknown qudit unitary channels. Using the framework of process positive operator valued measures (PPOVM) we characterize all solutions and identify the optimal ones. We prove that the entanglement is the key ingredient in designing the optimal experiment for comparison of unitary channels. Without entanglement the optimality can not be achieved. The proposed scheme is also experimentally feasible.
Cite
@article{arxiv.0809.4401,
title = {Unambiguous comparison of unitary channels},
author = {Michal Sedlak and Mario Ziman},
journal= {arXiv preprint arXiv:0809.4401},
year = {2009}
}
Comments
Version published in PRA, 7 pages, 1 figure