Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Negative entropy in quantum information theory   We present a quantum information theory that allows for the consistent
description of quantum entanglement. It parallels classical (Shannon)
information theory but is based entirely on density matrices, rather than
probability distributions, for the description of quantum ensembles. We find
that, unlike in Shannon theory, conditional entropies can be negative when
considering quantum entangled systems such as an Einstein-Podolsky-Rosen pair,
which leads to a violation of well-known bounds of classical information
theory. Negative quantum entropy can be traced back to ``conditional'' density
matrices which admit eigenvalues larger than unity. A straightforward
definition of mutual quantum entropy, or ``mutual entanglement'', can also be
constructed using a ``mutual'' density matrix. Such a unified
information-theoretic description of classical correlation and quantum
entanglement clarifies the link between them: the latter can be viewed as
``super-correlation'' which can induce classical correlation when considering a
ternary or larger system.

21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph