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Proceedings Paper

Optimal manipulations with qubits: universal quantum cloning and universal logical NOT operation
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Paper Abstract

We analyze how information encoded in quantum systems can be optimally processed. In particular, we investigate copying (cloning) of quantum information (represented as states of 2-level quantum systems--qubits). We present unitary transformations which describe the optimal universal cloning of a qubit. Universality of the transformation guarantees that the fidelity of the cloning does not depend on the input state of the qubit, i.e. all states are cloned equally well. We present network for the optimal universal quantum cloning `machine' (transformation) which produces N + 1 copies from the original qubit. Here again the quality (fidelity) of the copies does not depend on the state of the original and is only a function of the number of copes, N. We also present the `machine' which universally and optimally clones states of quantum objects in arbitrary- dimensional Hilbert spaces. In particular, we discuss universal cloning of quantum registers. In addition to cloning of qubits we analyzed another universal operation-- the Universal NOT. We present the optimal transformation and the corresponding logical network which optimally complements an arbitrary input state of a qubit. We show that the fidelity of the performance of the Universal NOT operation increases as a function of the number of input qubits prepared in the same state.

Paper Details

Date Published: 14 July 1999
PDF: 21 pages
Proc. SPIE 3820, 11th Slovak-Czech-Polish Optical Conference on Wave and Quantum Aspects of Contemporary Optics, (14 July 1999); doi: 10.1117/12.353044
Show Author Affiliations
Vladimir Buzek, Institute of Physics and Comenius Univ. (Slovak Republic)
Mark Hillery, CUNY/Hunter College (United States)


Published in SPIE Proceedings Vol. 3820:
11th Slovak-Czech-Polish Optical Conference on Wave and Quantum Aspects of Contemporary Optics
Miroslav Hrabovsky; Anton Strba; Waclaw Urbanczyk, Editor(s)

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