### Abstract

Language | English |
---|---|

Pages | 244-252 |

Number of pages | 9 |

Journal | Journal of Modern Optics |

Volume | 57 |

Issue number | 3 |

Early online date | 26 Aug 2009 |

DOIs | |

Publication status | Published - Jan 2010 |

### Fingerprint

### Keywords

- unambiguous discrimination
- optimum discrimination
- operator comparison
- generalized measurements
- fibre optics
- optoelectronics
- optics
- optoelectronic effects
- devices & systems

### Cite this

*Journal of Modern Optics*,

*57*(3), 244-252. https://doi.org/10.1080/09500340903203129

}

*Journal of Modern Optics*, vol. 57, no. 3, pp. 244-252. https://doi.org/10.1080/09500340903203129

**Decision problems with quantum black boxes.** / Hillery, Mark; Andersson, Erika; Barnett, Stephen M.; Oi, Daniel.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Decision problems with quantum black boxes

AU - Hillery, Mark

AU - Andersson, Erika

AU - Barnett, Stephen M.

AU - Oi, Daniel

PY - 2010/1

Y1 - 2010/1

N2 - We examine how to distinguish between unitary operators, when the exact form of the possible operators is not known. Instead we are supplied with 'programs' in the form of unitary transforms, which can be used as references for identifying the unknown unitary transform. All unitary transforms should be used as few times as possible. This situation is analogous to programmable state discrimination. One difference, however, is that the quantum state to which we apply the unitary transforms may be entangled, leading to a richer variety of possible strategies. By suitable selection of an input state and generalized measurement of the output state, both unambiguous and minimum-error discrimination can be achieved. Pairwise comparison of operators, comparing each transform to be identified with a program transform, is often a useful strategy. There are, however, situations in which more complicated strategies perform better. This is the case especially when the number of allowed applications of program operations is different from the number of the transforms to be identified.

AB - We examine how to distinguish between unitary operators, when the exact form of the possible operators is not known. Instead we are supplied with 'programs' in the form of unitary transforms, which can be used as references for identifying the unknown unitary transform. All unitary transforms should be used as few times as possible. This situation is analogous to programmable state discrimination. One difference, however, is that the quantum state to which we apply the unitary transforms may be entangled, leading to a richer variety of possible strategies. By suitable selection of an input state and generalized measurement of the output state, both unambiguous and minimum-error discrimination can be achieved. Pairwise comparison of operators, comparing each transform to be identified with a program transform, is often a useful strategy. There are, however, situations in which more complicated strategies perform better. This is the case especially when the number of allowed applications of program operations is different from the number of the transforms to be identified.

KW - unambiguous discrimination

KW - optimum discrimination

KW - operator comparison

KW - generalized measurements

KW - fibre optics

KW - optoelectronics

KW - optics

KW - optoelectronic effects

KW - devices & systems

UR - http://www.scopus.com/inward/record.url?scp=77951235006&partnerID=8YFLogxK

U2 - 10.1080/09500340903203129

DO - 10.1080/09500340903203129

M3 - Article

VL - 57

SP - 244

EP - 252

JO - Journal of Modern Optics

T2 - Journal of Modern Optics

JF - Journal of Modern Optics

SN - 0950-0340

IS - 3

ER -