Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Secret key distillation from shielded two-qubit states   The quantum states corresponding to a secret key are characterized using the
so-called private states, where the key part consisting of a secret key is
shielded by the additional systems. Based on the construction, it was shown
that a secret key can be distilled from bound entangled states. In this work, I
consider the shielded two-qubit states in a key-distillation scenario and
derive the conditions under which a secret key can be distilled using the
recurrence protocol or the two-way classical distillation, advantage
distillation together with one-way postprocessing. From the security
conditions, it is shown that a secret key can be distilled from bound entangled
states in a much wider range. In addition, I consider the case that in which
white noise is added to quantum states and show that the classical distillation
protocol still works despite a certain amount of noise although the recurrence
protocol does not.

21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an