Issue |
EPL
Volume 92, Number 2, October 2010
|
|
---|---|---|
Article Number | 20004 | |
Number of page(s) | 5 | |
Section | General | |
DOI | https://doi.org/10.1209/0295-5075/92/20004 | |
Published online | 16 November 2010 |
Global effects of quantum states induced by locally invariant measurements
1
Fakultät für Mathematik, Universität Bielefeld - 33615 Bielefeld, Germany, EU
2
Academy of Mathematics and Systems Science, Chinese Academy of Sciences - 100190 Beijing, PRC
Received:
21
August
2010
Accepted:
4
October
2010
In quantum mechanics, general measurements often cause disturbance which may be exploited to quantify entanglement, nonlocality or quantumness. Imagine a bipartite state ρab shared by two parties a and b, and a von Neumann measurement performed locally on party a which does not disturb the local state ρa≔tr bρab, but nevertheless may disturb the global state ρab. This disturbance is an indication of some kind of correlations or global effect in ρab which cannot be accounted for locally. We propose to use the maximum disturbance on ρab caused by locally non-disturbing measurements as a figure of merit quantifying the global effect (nonlocality), and investigate its fundamental properties. For general two-qubit states and some higher-dimensional symmetric states, we present analytic formulas for their global effects.
PACS: 03.65.Ta – Foundations of quantum mechanics; measurement theory / 03.65.Ud – Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.) / 03.67.-a – Quantum information
© EPLA, 2010
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