Scavenging quantum information: Multiple observations of quantum systems

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14330%2F11%3A00081781" target="_blank" >RIV/00216224:14330/11:00081781 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1103/PhysRevA.84.032326" target="_blank" >http://dx.doi.org/10.1103/PhysRevA.84.032326</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1103/PhysRevA.84.032326" target="_blank" >10.1103/PhysRevA.84.032326</a>

Result language
angličtina
Original language name
Scavenging quantum information: Multiple observations of quantum systems
Original language description
Given an unknown state of a qudit that has already been measured optimally, can one still extract any information about the original unknown state? Clearly, after a maximally informative measurement, the state of the system collapses into a postmeasurement state from which the same observer cannot obtain further information about the original state of the system. However, the system still encodes a significant amount of information about the original preparation for a second observer who is unaware of the actions of the first one. We study how a series of independent observers can obtain, or can scavenge, information about the unknown state of a system (quantified by the fidelity) when they sequentially measure it. We give closed-form expressions for the estimation fidelity when one or several qudits are available to carry information about the single-qudit state, and we study the classical limit when an arbitrarily large number of observers can obtain (nearly) complete information on
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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Publication year
2011
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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