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[MMIX Outlandish]

MMIX Outlandish

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FUNEX? S, VFX. FUNEM? S, VFM

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Date Registered:

May 16, 2009, 04:57:54 pm

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May 22, 2013, 10:16:45 am

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Quantum discord quantifies nonclassical correlations in a quantum system including those not captured by entanglement. Thus, only states with zero discord exhibit strictly classical correlations. We prove that these states are negligible in the whole Hilbert space: typically a state picked out at random has positive discord and, given a state with zero discord, a generic arbitrarily small perturbation drives it to a positive-discord state. These results hold for any Hilbert-space dimension and have direct implications for quantum computation and for the foundations of the theory of open systems. In addition, we provide a simple necessary criterion for zero quantum discord. Finally, we show that, for almost all positive- discord states, an arbitrary Markovian evolution cannot lead to a sudden, permanent vanishing of discord.