Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Complete controllability of finite quantum systems with two-fold energy
  level degeneracy   Complete controllability of finite dimensional quantum systems with energy
level degeneracy is investigated using two different approaches. One approach
is to apply a weak constant field to eliminate the degeneracy and then control
it using techniques developed for non-degenerate quantum systems. Conditions
for the elimination of degeneracy are found and the issue of influence of
relaxation time of constant external field to the target state are addressed
through the fidelity. Another approach is to control the degenerate system by a
single control field directly. It is found that the system with two-fold
degenerate excited states and non-degenerate ground state are completely
controllable except for the two-level system. Conditions of complete
controllability are found for both systems with different energy gaps and with
equal energy gaps.

34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio