Physical Review A, ( ISI ), Volume (94), No (5), Year (2016-11) , Pages (1-11)

Title : ( Two-qubit quantum cloning machine and quantum correlation broadcasting )

Authors: A. Kheirollahi , Hamidreza Mohammadi , Seyed Javad Akhtarshenas ,

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Due to the axioms of quantum mechanics, perfect cloning of an unknown quantum state is impossible. But since imperfect cloning is still possible, a question arises: “Is there an optimal quantum cloning machine?” Buzek and Hillery answered this question and constructed their famous B-H quantum cloning machine. The B-H machine clones the state of an arbitrary single qubit in an optimal manner and hence it is universal. Generalizing this machine for a two-qubit system is straightforward, but during this procedure, except for product states, this machine loses its universality and becomes a state-dependent cloning machine. In this paper, we propose some classes of optimal universal local quantum state cloners for a particular class of two-qubit systems, more precisely, for a class of states with known Schmidt basis.We then extend our machine to the case that the Schmidt basis of the input state is deviated from the local computational basis of the machine. We show that more local quantum coherence existing in the input state corresponds to less fidelity between the input and output states. Also we present two classes of a state-dependent local quantum copying machine. Furthermore, we investigate local broadcasting of two aspects of quantum correlations, i.e., quantum entanglement and quantum discord, defined, respectively, within the entanglement-separability paradigm and from an information-theoretic perspective. The results show that although quantum correlation is, in general, very fragile during the broadcasting procedure, quantum discord is broadcasted more robustly than quantum entanglement.


, Local broadcasting, Quantum cloning machine, Pauli channel, Quantum correlation
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author = {A. Kheirollahi and Hamidreza Mohammadi and Akhtarshenas, Seyed Javad},
title = {Two-qubit quantum cloning machine and quantum correlation broadcasting},
journal = {Physical Review A},
year = {2016},
volume = {94},
number = {5},
month = {November},
issn = {2469-9926},
pages = {1--11},
numpages = {10},
keywords = {Local broadcasting; Quantum cloning machine; Pauli channel; Quantum correlation},


%0 Journal Article
%T Two-qubit quantum cloning machine and quantum correlation broadcasting
%A A. Kheirollahi
%A Hamidreza Mohammadi
%A Akhtarshenas, Seyed Javad
%J Physical Review A
%@ 2469-9926
%D 2016