Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Narrow Bounds for the Quantum Capacity of Thermal Attenuators   Thermal attenuator channels model the decoherence of quantum systems
interacting with a thermal bath, e.g., a two-level system subject to thermal
noise and an electromagnetic signal travelling through a fiber or in
free-space. Hence determining the quantum capacity of these channels is an
outstanding open problem for quantum computation and communication. Here we
derive several upper bounds on the quantum capacity of qubit and bosonic
thermal attenuators. We introduce an extended version of such channels which is
degradable and hence has a single-letter quantum capacity, bounding that of the
original thermal attenuators. Another bound for bosonic attenuators is given by
the bottleneck inequality applied to a particular channel decomposition. With
respect to previously known bounds we report better results in a broad range of
attenuation and noise: we can now approximate the quantum capacity up to a
negligible uncertainty for most practical applications, e.g., for low thermal
noise.

18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an