Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Minimum error discrimination of qubit states revisited   We study the problem of minimum-error discrimination for qubit states with a
simple geometric approach. For this purpose, we employ the Helstrom conditions
in a constructive way and use the Bloch vector formulation. Our method is based
on the Lagrange operator $\Gamma$. To find $\Gamma$, we introduce the notion of
circumsphere for equiprobable problems. Furthermore, for a general problem with
arbitrary prior probabilities we introduce a structured instruction with some
practical tips involving the polytope of states. With knowing $\Gamma$, we are
able to find all of the possible ME discrimination measurements of the problem.
As an application of this instruction, we study the problem of three qubit
states completely and for comparison to previous results, we solve the problem
of trine states with arbitrary a priori probabilities. We define the concept of
decomposable measurements which can be useful in practical situations.

9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph