Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the role of coherent attacks in a type of strategic problem related
  to quantum key distribution   We consider a strategic problem of the Evesdropping to quantum key
distribution. Evesdropper hopes to obtain the maxium information given the
disturbance to the qubits is often For this strategy, the optimized individual
attack have been extensively constructed under various conditions. However, it
seems a difficult task in the case of coherent attack, i.e., Eve may treat a
number of intercepted qubits collectively, including the collective unitary
transformations and the measurements. It was conjectured by Cirac and Gisin
that no coherent attack can be more powerful for this strategy for BB84
protocol. In this paper we give a general conclusion on the role of coherent
attacks for the strategy of maxmizing the information given the disturbance.
Suppose in a quantum key distribution(QKD) protocol, all the transmitted bits
from Alice are independent and only the individual disturbances to each qubits
are examined by Alice and Bob. For this type of protocols(so far almost all QKD
protocols belong to this type), in principle no coherent attack is more
powerful than the product of optimized individual attack to each individual
qubits. All coherent attacks to the above QKD protocols can be disregarded for
the strategy above.

27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol