Quantum Fisher information of the GHZ state due to classical phase noise lasers under non-Markovian environment

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• 作者：Yu Chen^a ; ^b ; ^{chenyuchn@163.com" class="auth_mail" title="E-mail the corresponding author} ; Jian Zou^a ; Zi-Yi Yang^c ; Longwu Li^d ; Hai Li^e ; Bin Shao^a
• 关键词：Quantum Fisher information ; GHZ state ; Non-Markovian dynamics ; Phase noise laser ; Random telegraph noise
• 刊名：Annals of Physics
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：371
• 期：Complete
• 页码：379-397
• 全文大小：1184 K

文摘

The dynamics of science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0003491616300847&_mathId=si8.gif&_user=111111111&_pii=S0003491616300847&_rdoc=1&_issn=00034916&md5=891abe53d907b1155edfb1287f9bbd67" title="Click to view the MathML source">N$N$-qubit GHZ state quantum Fisher information (QFI) under phase noise lasers (PNLs) driving is investigated in terms of non-Markovian master equation. We first investigate the non-Markovian dynamics of the QFI of science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0003491616300847&_mathId=si8.gif&_user=111111111&_pii=S0003491616300847&_rdoc=1&_issn=00034916&md5=891abe53d907b1155edfb1287f9bbd67" title="Click to view the MathML source">N$N$-qubit GHZ state and show that when the ratio of the PNL rate and the system–environment coupling strength is very small, the oscillations of the QFIs decay slower which corresponds to the non-Markovian region; yet when it becomes large, the QFIs monotonously decay which corresponds to the Markovian region. When the atom number science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0003491616300847&_mathId=si8.gif&_user=111111111&_pii=S0003491616300847&_rdoc=1&_issn=00034916&md5=891abe53d907b1155edfb1287f9bbd67" title="Click to view the MathML source">N$N$ increases, QFIs in both regions decay faster. We further find that the QFI flow disappears suddenly followed by a sudden birth depending on the ratio of the PNL rate and the system–environment coupling strength and the atom number science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0003491616300847&_mathId=si8.gif&_user=111111111&_pii=S0003491616300847&_rdoc=1&_issn=00034916&md5=891abe53d907b1155edfb1287f9bbd67" title="Click to view the MathML source">N$N$, which unveil a fundamental connection between the non-Markovian behaviors and the parameters of system–environment couplings. We discuss two optimal positive operator-valued measures (POVMs) for two different strategies of our model and find the condition of the optimal measurement. At last, we consider the QFI of two atoms with qubit–qubit interaction under random telegraph noises (RTNs).