469 research outputs found
General theory of environment-assisted entanglement distillation
We evaluate the one-shot entanglement of assistance for an arbitrary
bipartite state. This yields another interesting result, namely a
characterization of the one-shot distillable entanglement of a bipartite pure
state. This result is shown to be stronger than that obtained by specializing
the one-shot hashing bound to pure states. Finally, we show how the one-shot
result yields the operational interpretation of the asymptotic entanglement of
assistance proved in [Smolin et al., Phys. Rev. A 72, 052317 (2005)].Comment: 23 pages, one column, final published versio
The quantum capacity of channels with arbitrarily correlated noise
We study optimal rates for quantum communication over a single use of a
channel, which itself can correspond to a finite number of uses of a channel
with arbitrarily correlated noise. The corresponding capacity is often referred
to as the one-shot quantum capacity. In this paper, we prove bounds on the
one-shot quantum capacity of an arbitrary channel. This allows us to compute
the quantum capacity of a channel with arbitrarily correlated noise, in the
limit of asymptotically many uses of the channel. In the memoryless case, we
explicitly show that our results reduce to known expressions for the quantum
capacity.Comment: 15 pages, two columns. Final improved version - to appear in IEE
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