Quantum disentanglers

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14330%2F00%3A00002895" target="_blank" >RIV/00216224:14330/00:00002895 - isvavai.cz</a>
Result on the web
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DOI - Digital Object Identifier
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Result language
angličtina
Original language name
Quantum disentanglers
Original language description
It is not possible to disentangle a qubit in an unknown state psi > from a set of N-1 ancilla qubits prepared in a specific reference state >. That is, it is not possible to perfectly perform the transformation ( psi ,0,...,0 > + ,psi,...,0 > +...+.0,...,0 psi >) --> ,...,0 > circle times psi >. The question is then how well we can do? We consider a number of different methods of extracting an unknown state from an entangled state formed from that qubit and a set of ancilla qubits in a known state. Measuring the whole system is, as expected, the least effective method. We present various quantum ''devices'' which disentangle the unknown qubit from the set of ancilla qubits. In particular, we present the optimal universal disentangler which disentangles the unknown qubit with a fidelity that does not depend on the state of the qubit, and a probabilistic disentangler which performs the perfect disentangling transformation, but with a probability less than 1.
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BE - Theoretical physics
OECD FORD branch
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Project
<a href="/en/project/GA201%2F98%2F0369" target="_blank" >GA201/98/0369: Informatics as the third methodology</a><br>
Continuities
Z - Vyzkumny zamer (s odkazem do CEZ)

Publication year
2000
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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