Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Magneto-optical probing of weak disorder in a two-dimensional hole gas   In two-beam magneto-photoluminescence spectra of a two-dimensional valence
hole gas we identify the three-level energy spectrum of a free positive trion
with a field-induced singlet-triplet transition. The recombination spectrum of
acceptor-bound trions is also detected, including a cyclotron replica
corresponding to the hole shake-up process. The emergence of a shake-up peak at
low temperature is shown to be a sensitive probe of the presence of a small
number of impurities inside the high-mobility quantum well, and its relative
position is directly related to the hole cyclotron mass.

20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th