Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Universal quantum Controlled-NOT gate   An investigation of an optimal universal unitary Controlled-NOT gate that
performs a specific operation on two unknown states of qubits taken from a
great circle of the Bloch sphere is presented. The deep analogy between the
optimal universal C-NOT gate and the `equatorial' quantum cloning machine (QCM)
is shown. In addition, possible applications of the universal C-NOT gate are
briefly discussed.

5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg