Pilot-assisted intradyne reception for high-speed continuous-variable quantum key distribution with true local oscillator

Fabian Laudenbach; Bernhard Schrenk; Christoph Pacher; Michael Hentschel; Chi-Hang Fred Fung; Fotini Karinou; Andreas Poppe; Momtchil Peev; Hannes Hübel

doi:10.22331/q-2019-10-07-193

Pilot-assisted intradyne reception for high-speed continuous-variable quantum key distribution with true local oscillator

Fabian Laudenbach^1,2, Bernhard Schrenk¹, Christoph Pacher¹, Michael Hentschel¹, Chi-Hang Fred Fung³, Fotini Karinou³, Andreas Poppe³, Momtchil Peev³, and Hannes Hübel¹

¹Security & Communication Technologies, Center for Digital Safety & Security, AIT Austrian Institute of Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
²Quantum Optics, Quantum Nanophysics & Quantum Information, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria
³Optical and Quantum Laboratory, Munich Research Center, Huawei Technologies Duesseldorf GmbH, Riesstrasse 25-C3, 80992 Munich, Germany

Published:	2019-10-07, volume 3, page 193
Eprint:	arXiv:1712.10242v4
Doi:	https://doi.org/10.22331/q-2019-10-07-193
Citation:	Quantum 3, 193 (2019).

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Abstract

We present a pilot-assisted coherent intradyne reception methodology for CV-QKD with true local oscillator. An optically phase-locked reference tone, prepared using carrier-suppressed optical single-sideband modulation, is multiplexed in polarisation and frequency to the 250 Mbaud quantum signal in order to provide optical frequency- and phase matching between quantum signal and local oscillator. Our concept allows for high symbol rates and can be operated at an extremely low excess-noise level, as validated by experimental measurements.

Popular summary

Quantum key distribution (QKD) is a method to establish symmetric encryption keys at two distant sites. Thanks to the Heisenberg uncertainty principle and the so-called no-cloning theorem, these keys are guaranteed to be exclusively known by the trusted communicators. Any potential attempt to eavesdrop on the key exchange will inevitalbly disturb the transmitted quantum states and can therefore be easily detected -- this is why QKD is secured on a physical layer, in contrast to public-key encryption which relies on computational hardness assumptions.

QKD can be exercised with both, single photons or weak coherent states. The latter approach encodes the quantum information in the continuous phase and amplitude of the electromagnetic field of light and is therefore referred to as continuous-variable quantum key distribution (CV-QKD). As a main advantage of CV-QKD, this approach uses standard off-the-shelf components from the optical-telecommunication industry and can therefore be seamlessly integrated into existing telecom networks.

This article addresses an open problem in CV-QKD: to establish a stable phase- and frequency reference between transmitter and receiver (required for coherent detection) that does neither compromise the low noise level nor the symbol rate. As we believe, our method to co-transmit an optical reference signal, multiplexed to the quantum signal in modulation frequency and polarisation, constitutes a convincing answer to this problem. Harnessing the best practices from the highly advnced telecom industry, our transceiver operates at exceptionally high rate and low noise and thereby elevates QKD to a new level of technological maturity.

► BibTeX data

@article{Laudenbach2019pilotassisted,
  doi = {10.22331/q-2019-10-07-193},
  url = {https://doi.org/10.22331/q-2019-10-07-193},
  title = {Pilot-assisted intradyne reception for high-speed continuous-variable quantum key distribution with true local oscillator},
  author = {Laudenbach, Fabian and Schrenk, Bernhard and Pacher, Christoph and Hentschel, Michael and Fung, Chi-Hang Fred and Karinou, Fotini and Poppe, Andreas and Peev, Momtchil and H{\"{u}}bel, Hannes},
  journal = {{Quantum}},
  issn = {2521-327X},
  publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}},
  volume = {3},
  pages = {193},
  month = oct,
  year = {2019}
}

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