Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parity effect in Al and Nb single electron transistors in a tunable
  environment   Two different types of Cooper pair transistors, with Al and Nb islands, have
been investigated in a tunable electromagnetic environment. The device with an
Al island demonstrates gate charge modulation with 2e-periodicity in a wide
range of environmental impedances at bath temperatures below 340 mK. Contrary
to the results of the Al sample, we were not able to detect 2e-periodicity
under any conditions on similar samples with Nb island. We attribute this to
the material properties of Nb.

23
The categories of this paper are: solv-int
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The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess