Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Field Experimental "Star Type" Metropolitan Quantum Key Distribution
  Network   Quantum key distribution (QKD) network has recently attracted growing
attentions. Due to the special characteristics of quantum information, to build
a full-connectivity QKD network without trusted relays is a stimulating
challenge. In this letter, we report on the first realization of QKD network
without trusted relays which covers metropolis in the commercial backbone
optical fiber networks. The star topology four-user QKD network automatically
addresses the quantum signal with a quantum router (QR) and every user in the
network can receive and distribute quantum keys to any others simultaneously.
The longest and the shortest length of fibers between two geographically
separated nodes are 42.6km and 32km respectively, and the maximum average
quantum bit error rate (QBER) is below 8%. This result opens a new possibility
for the use of QKD into existing network.

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The categories of this paper are: cmp-lg
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The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
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
12
The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat