Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct and indirect exciton mixture in double quantum wells   The exciton system in double quantum well is considered under condition when
the ground state is the spatially indirect exciton. At high pumping growth of
the exciton concentration can lead to so significant increase of the indirect
exciton energy that becomes equal to the direct exciton energy. Then further
increase of pumping leads to formation of mixed direct - indirect exciton
phase. A rough estimate of the exciton energy in the mixed phase explains
puzzling features of some recent exciton measurements. An experiment that would
reveal main characteristic features of the mixed phase is suggested.

5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
10
The categories of this paper are: q-bio