Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The von Neumann entropy and unitary equivalence of quantum states   K. He, J. Hou, and M. Li have recently given a sufficient and necessary
condition for unitary equivalence of quantum states. This condition is based on
the von Neumann entropy. In this note we first give a short proof of their
result, and then we improve it.

25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
7
The categories of this paper are: hep-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-th