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Direct estimations of linear and nonlinear functionals of a quantum state
Citation
Ekert, A. K., Alves, C. M., Oi, D. K. L., Horodecki, M., Horodecki, P., & Kwek, L. C. (2002). Direct estimations of linear and nonlinear functionals of a quantum state. Physical Review Letters, 88(21), Article 217901. http://doi.org/10.1103/PhysRevLett.88.217901
Author
Ekert, Artur K.
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Alves, Carolina Moura
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Oi, Daniel K. L.
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Horodecki, Michal
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Horodecki, Pawel
•
Abstract
We present a simple quantum network, based on the controlled-SWAP gate, that can extract certain properties of quantum states without recourse to quantum tomography. It can be used used as a basic building block for direct quantum estimations of both linear and non-linear functionals of any density operator. The network has many potential applications ranging from purity tests and eigenvalue estimations to direct characterization of some properties of quantum channels. Experimental realizations of the proposed network are within the reach of quantum technology that is currently being developed.
Date Issued
2002
Publisher
American Physical Society
Journal
Physical Review Letters
DOI
10.1103/PhysRevLett.88.217901