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Nanosystems Physics Chemistry Mathematics

Temperature dependence of the optical fiber cable parameters in subcarrier wave quantum communication systems

V.D. Dubrovskaia, Sergey A. Chivilikhin

Published Apr 20, 2016• 2 citations
Publisher

Abstract

A common approach to establishing long-distance synchronization links in quantum communication (QC) systems is based on using optical signals transmitted in cables, where they decay and are distorted.It is necessary to evaluate the transformation of the signal parameters during propagation and their influence on the QC systems.We investigate the temperature dependence of the synchronization signal phase of a subcarrier wave quantum communication system (SCWQC) in optical fiber cables.A temperature model was created in order to determine the signal phase delay in the cable.We estimate the influence of daily temperature fluctuations on the phase delay in ground-and air-based cables.For systems operating with ground-based cables, they do not have any significant impact on the synchronization of the signal phase.However, for systems operating through air-based cables, phase adjustment is required every 158 ms for stable operation.This allowed us to optimize the parameters for a calibration procedure of a previously-developed SCWQC system, increasing the overall sifted key generation rate.

DOI
10.17586/2220-8054-2016-7-2-371-377

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A common approach to establishing long-distance synchronization links in quantum communication (QC) systems is based on using optical signals transmitted in cables, where they decay and are distorted.It is necessary to evaluate the transformation of the signal parameters during propagation and their influence on the QC systems.We investigate the temperature dependence of the synchronization signal phase of a subcarrier wave quantum communication system (SCWQC) in optical fiber cables.A temperature model was created in order to determine the signal phase delay in the cable.We estimate the influence of daily temperature fluctuations on the phase delay in ground-and air-based cables.For systems operating with ground-based cables, they do not have any significant impact on the synchronization of the signal phase.However, for systems operating through air-based cables, phase adjustment is required every 158 ms for stable operation.This allowed us to optimize the parameters for a calibration procedure of a previously-developed SCWQC system, increasing the overall sifted key generation rate.
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An important problem in the practical implementation of fiber optical quantum communication systems is to synchronize the sender and receiver modules using a separate optical channel.The signal visibility in the quantum channel, which contributes to quantum bit error rate, is influenced by the synchronization signal delay.In this work, we investigate the dependence of the synchronization signal parameters on the dispersive effects in the fiber for a subcarrier wave quantum communication system (SCWQC), which is promising for quantum networking applications.The ITU-T G.652D standard single mode optical fiber was used for modeling.The maximum calculated phase mismatch of the synchronization signal for the system operating at 100 km fiber length corresponds to 1.7 ps signal time delay.The results show that dispersion causes significant signal distortion, therefore additional phase adjustment at least every 2.3 hours is required for stable system operation.
In this paper, we consider the influence of a divergence of polarization of a quantum signal transmitted through an optical fiber channel on the quantum bit error rate of the subcarrier wave quantum key distribution protocol. Firstly, we investigate the dependence of the optical power of the signal on the modulation indices' difference after the second phase modulation of the signal. Then we consider the Liouville equation with regard to relaxation in order to develop expressions of the dynamics of the Stokes parameters. As a result, we propose a model that describes quantum bit error rate for the subcarrier wave quantum key distribution depending on the characteristics of the optical fiber. Finally, we propose several methods for minimizing quantum bit error rate.
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