Violation of the “information–disturbance relationship” in finite-time quantum measurements
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The effect of measurement attributes (quantum level of precision, finite duration) on the classical and quantum correlations is analyzed for a pair of qubits immersed in a common reservoir. We show that the quantum discord is enhanced as the precision of the measuring instrument is increased, and both the classical correlation and the quantum discord experience noticeable changes during finite-time measurements performed on a neighboring partition of the entangled system. The implication of these results on the “information–disturbance relationship” is examined, with critical analysis of the delicate roles played by quantum non-locality and non-Markovian dynamics in the violation of this relationship, which appears surprisingly for a range of measurement attributes. This work highlights that the fundamental limits of quantum mechanical measurements can be altered by exchanges of non-classical correlations such as the quantum discord with external sources, which has relevance to cryptographic technology.
KeywordsQuantum correlations Quantum measurements Non-Markovian dynamics Information–disturbance relationship Quantum cryptography
This research was undertaken on the NCI National Facility in Canberra, Australia, which is supported by the Australian Commonwealth Government. The author gratefully acknowledges the support of the Julian Schwinger Foundation Grant, JSF-12-06-0000. The author would like to thank the anonymous referees for helpful comments.
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