Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probability representation of quantum observable and quantum states   We introduce the probability distributions describing quantum observables in
conventional quantum mechanics and clarify their relations to the tomographic
probability distributions describing quantum states. We derive the evolution
equation for quantum observables (Heisenberg equation) in the probability
representation and give examples of the spin-1/2 (qubit) states and the spin
observables. We present quantum channels for qubits in the probability
representation.

30
The categories of this paper are: q-alg
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn