Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comments on the observation of quantum oscillations in cuprates   This paper comments on the recently reported quantum oscillations in
underdoped YBCO crystals. The implications to other experiments and some
hurdles to validating the proposed interpretation are discussed.

28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph