Ancilla-Assisted Discrimination of Quantum Gates
| dc.creator | Chen, Jianxin | |
| dc.creator | Ying, Mingsheng | |
| dc.date | 2008-09-02 | |
| dc.date.accessioned | 2026-07-07T09:59:55Z | |
| dc.date.available | 2026-07-07T09:59:55Z | |
| dc.description | The intrinsic idea of superdense coding is to find as many gates as possible such that they can be perfectly discriminated. In this paper, we consider a new scheme of discrimination of quantum gates, called ancilla-assisted discrimination, in which a set of quantum gates on a $d-$dimensional system are perfectly discriminated with assistance from an $r-$dimensional ancilla system. The main contribution of the present paper is two-fold: (1) The number of quantum gates that can be discriminated in this scheme is evaluated. We prove that any $rd+1$ quantum gates cannot be perfectly discriminated with assistance from the ancilla, and there exist $rd$ quantum gates which can be perfectly discriminated with assistance from the ancilla. (2) The dimensionality of the minimal ancilla system is estimated. We prove that there exists a constant positive number $c$ such that for any $k\leq cr$ quantum gates, if they are $d$-assisted discriminable, then they are also $r$-assisted discriminable, and there are $c^{\prime}r\textrm{}(c^{\prime}>c)$ different quantum gates which can be discriminated with a $d-$dimensional ancilla, but they cannot be discriminated if the ancilla is reduced to an $r-$dimensional system. Thus, the order $O(r)$ of the number of quantum gates that can be discriminated with assistance from an $r-$dimensional ancilla is optimal. The results reported in this paper represent a preliminary step toward understanding the role ancilla system plays in discrimination of quantum gates as well as the power and limit of superdense coding. | |
| dc.identifier | https://arxiv.org/abs/0809.0336 | |
| dc.identifier | http://arxiv.org/abs/0809.0336 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/168196 | |
| dc.subject | Quantum Physics | |
| dc.title | Ancilla-Assisted Discrimination of Quantum Gates | |
| dc.type | text |