Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing the helical edge states of a topological insulator by
  Cooper-pair injection   We consider the proximity effect between a singlet s-wave superconductor and
the edge of a Quantum Spin Hall (QSH) topological insulator. We establish that
Andreev reflection at a QSH edge state/superconductor interface is perfect
while nonlocal Andreev processes through the superconductor are totally
suppressed. We compute the corresponding conductance and noise.

13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an