Wednesday, February 6, 2013

1302.1011 (Z. -H. Ma et al.)

A universal, memory-assisted entropic uncertainty relation    [PDF]

Z. -H. Ma, C. -M. Yao, Z. -H. Chen, S. Severini, A. Serafini
We derive a new memory-assisted entropic uncertainty relation for non-degenerate Hermitian observables where both quantum correlations, in the form of conditional von Neumann entropy, and quantum discord between system and memory play an explicit role. Our relation is `universal', in the sense that it does not depend on the specific observable, but only on properties of the quantum state. We contrast such an uncertainty relation with previously known memory-assisted relations based on entanglement and correlations. Further, we present a detailed comparative study of entanglement- and discord-assisted entropic uncertainty relations for systems of two qubits -- one of which plays the role of the memory -- subject to several forms of independent quantum noise, in both Markovian and non-Markovian regimes. We thus show explicitly that, partly due to the ubiquity and inherent resilience of quantum discord, discord-tightened entropic uncertainty relations often offer a better estimate of the uncertainties in play.
View original: http://arxiv.org/abs/1302.1011

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