Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Experimental study on Gaussian-modulated coherent states quantum key
  distribution over standard telecom fiber   In this paper, we present a fully fiber-based one-way Quantum Key
Distribution (QKD) system implementing the Gaussian-Modulated Coherent States
(GMCS) protocol. The system employs a double Mach-Zehnder Interferometer (MZI)
configuration in which the weak quantum signal and the strong Local Oscillator
(LO) go through the same fiber between Alice and Bob, and are separated into
two paths inside Bob's terminal. To suppress the LO leakage into the signal
path, which is an important contribution to the excess noise, we implemented a
novel scheme combining polarization and frequency multiplexing, achieving an
extinction ratio of 70dB. To further minimize the system excess noise due to
phase drift of the double MZI, we propose that, instead of employing phase
feedback control, one simply let Alice remap her data by performing a rotation
operation. We further present noise analysis both theoretically and
experimentally. Our calculation shows that the combined polarization and
frequency multiplexing scheme can achieve better stability in practice than the
time-multiplexing scheme, because it allows one to use matched fiber lengths
for the signal and the LO paths on both sides of the double MZI, greatly
reducing the phase instability caused by unmatched fiber lengths. Our
experimental noise analysis quantifies the three main contributions to the
excess noise, which will be instructive to future studies of the GMCS QKD
systems. Finally, we demonstrate, under the "realistic model" in which Eve
cannot control the system within Bob's terminal, a secure key rate of
0.3bit/pulse over a 5km fiber link. This key rate is about two orders of
magnitude higher than that of a practical BB84 QKD system.

16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas