Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Distillation of secret key from a class of compound memoryless quantum
  sources   We consider secret-key distillation from tripartite compound
classical-quantum-quantum (cqq) sources with free forward public communication
under strong security criterion. We design protocols which are universally
reliable and secure in this scenario. These are shown to achieve asymptotically
optimal rates as long as a certain regularity condition is fulfilled by the the
set of its generating density matrices. We derive a multi-letter formula which
describes the optimal forward secret-key capacity for all compound cqq sources
being regular in this sense. We also determine the forward secret-key
distillation capacity for situations, where the legitimate sending party has
perfect knowledge of his/her marginal state deriving from the source
statistics. In this case regularity conditions can be dropped. Our results show
that the capacities with and without the mentioned kind of state knowledge are
equal as long as the source is generated by a regular set of density matrices.
We demonstrate that regularity of cqq sources is not only a technical but also
an operational issue. For this reason, we give an example of a source which has
zero secret-key distillation capacity without sender knowledge, while achieving
positive rates is possible if sender marginal knowledge is provided.

24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg