Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Experimental demonstration of a quantum receiver beating the standard
  quantum limit at the telecom wavelength   Discrimination of coherent states beyond the standard quantum limit (SQL) is
an important tasknot only for quantum information processing but also for
optical coherent communication. In orderto optimize long distance optical fiber
networks, it is of practical importance to develop a quantumreceiver beating
the SQL and approaching the quantum bound at telecom wavelength. In this
paper,we experimentally demonstrate a receiver beating the conventional SQL at
telecom wavelength. Ourreceiver is composed of a displacement operation, a
single photon counter and a real time adaptivefeedback operation. By using a
high performance single photon detector operating at the telecomwavelength, we
achieve a discrimination error beyond the SQL. The demonstration in the
telecomband provides the first step important towards quantum and classical
communication beyond theSQL using a coherent state alphabet, and we envision
that the technology can be used for long-distance quantum key distribution,
effective quantum state preparation and quantum estimation.

37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat