Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Continuous-variable quantum cryptography with an untrusted relay:
  Detailed security analysis of the symmetric configuration   We consider the continuous-variable protocol of Pirandola et al. [Nature
Photonics 9, 397-402 (2015), see also arXiv.1312.4104] where the secret-key is
established by the measurement of an untrusted relay. In this network protocol,
two authorized parties are connected to an untrusted relay by insecure quantum
links. Secret correlations are generated by a continuous-variable Bell
detection performed on incoming coherent states. In the present work we provide
a detailed study of the symmetric configuration, where the relay is midway
between the parties. We analyze symmetric eavesdropping strategies against the
quantum links explicitly showing that, at fixed transmissivity and thermal
noise, two-mode coherent attacks are optimal, manifestly outperforming one-mode
collective attacks based on independent entangling cloners. Such an advantage
is shown both in terms of security threshold and secret-key rate.

23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat