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Quantum Fisher information of a qubit initially correlated with a non-Markovian environment

Quantum Fisher information of a qubit initially correlated with a non-Markovian environment The quantum Fisher information in phase estimation is investigated for a qubit which is placed under the influence of a non-Markovian environment. The multi-mode Jaynes–Cummings model which has at least one excitation is used as a qubit-environment model. It is examined how initial correlation between the qubit and the environment affects time evolution of the quantum Fisher information. Although information on the phase parameter is included only in off-diagonal elements of the reduced density matrix of the qubit in the absence of the initial correlation, it is included not only in off-diagonal elements but also in diagonal elements in the presence of the initial correlation. This implies that the quantum Fisher information is greatly affected by the initial correlation. In particular, when the time evolution of the reduced density operator of the qubit is non-Markovian, the quantum Fisher information can take values greater than its initial value due to the initial correlation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Quantum Information Processing Springer Journals

Quantum Fisher information of a qubit initially correlated with a non-Markovian environment

Quantum Information Processing , Volume 14 (11) – Aug 29, 2015

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References (51)

Publisher
Springer Journals
Copyright
Copyright © 2015 by Springer Science+Business Media New York
Subject
Physics; Quantum Information Technology, Spintronics; Quantum Computing; Data Structures, Cryptology and Information Theory; Quantum Physics; Mathematical Physics
ISSN
1570-0755
eISSN
1573-1332
DOI
10.1007/s11128-015-1097-7
Publisher site
See Article on Publisher Site

Abstract

The quantum Fisher information in phase estimation is investigated for a qubit which is placed under the influence of a non-Markovian environment. The multi-mode Jaynes–Cummings model which has at least one excitation is used as a qubit-environment model. It is examined how initial correlation between the qubit and the environment affects time evolution of the quantum Fisher information. Although information on the phase parameter is included only in off-diagonal elements of the reduced density matrix of the qubit in the absence of the initial correlation, it is included not only in off-diagonal elements but also in diagonal elements in the presence of the initial correlation. This implies that the quantum Fisher information is greatly affected by the initial correlation. In particular, when the time evolution of the reduced density operator of the qubit is non-Markovian, the quantum Fisher information can take values greater than its initial value due to the initial correlation.

Journal

Quantum Information ProcessingSpringer Journals

Published: Aug 29, 2015

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