426 research outputs found
Strong polygamy of quantum correlations in multi-party quantum systems
We propose a new type of polygamy inequality for multi-party quantum
entanglement. We first consider the possible amount of bipartite entanglement
distributed between a fixed party and any subset of the rest parties in a
multi-party quantum system. By using the summation of these distributed
entanglements, we provide an upper bound of the distributed entanglement
between a party and the rest in multi-party quantum systems. We then show that
this upper bound also plays as a lower bound of the usual polygamy inequality,
therefore the strong polygamy of multi-party quantum entanglement. For the case
of multi-party pure states, we further show that the strong polygamy of
entanglement implies the strong polygamy of quantum discord.Comment: 5 page
Bound entangled states with nonzero distillable key rate
In this paper, we present sufficient conditions for states to have positive
distillable key rate. Exploiting the conditions, we show that the bound
entangled states given by Horodecki et al. [Phys. Rev. Lett. 94, 160502 (2005),
quant-ph/0506203] have nonzero distillable key rate, and finally exhibit a new
class of bound entangled states with positive distillable key rate, but with
negative Devetak-Winter lower bound of distillable key rate for the ccq states
of their privacy squeezed versions.Comment: 7 pages, 1 figure, typos corrected, accepted for publication in PR
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