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Journal of Lightwave Technology

Dual-Threshold Balanced Homodyne Detection at 1550 nm Optical Fiber Quantum Key Distribution System

Qing Xu, Manuel Sabban, M. B. Costa e Silva, Philippe B. Gallion, Francisco Javier Mendieta

Published Apr 18, 2009• 9 citations
Publisher

Abstract

We present a flexible quantum key distribution (QKD) system implementation using quadrature phase-shift keying (QPSK) encoding. Two detection techniques are implemented and compared: a photon counting detection scheme using single photon avalanche diodes (SPAD) and a dual-threshold balanced homodyne detection (BHD) using standard PIN diodes in which the weak signal is time-multiplexed with a strong reference. The interferometer instability and the system phase fluctuations are compensated by an optoelectronic feedback loop that allows an automatic continuous operation. We compare the QKD system performance for both schemes in terms of BER and key generation efficiency. Finally, we analyze the BHD QKD system security under the potential individual intercept-resend attack and the intermediate-base attack.

DOI
10.1109/jlt.2008.2009949

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We present a flexible quantum key distribution (QKD) system implementation using quadrature phase-shift keying (QPSK) encoding. Two detection techniques are implemented and compared: a photon counting detection scheme using single photon avalanche diodes (SPAD) and a dual-threshold balanced homodyne detection (BHD) using standard PIN diodes in which the weak signal is time-multiplexed with a strong reference. The interferometer instability and the system phase fluctuations are compensated by an optoelectronic feedback loop that allows an automatic continuous operation. We compare the QKD system performance for both schemes in terms of BER and key generation efficiency. Finally, we analyze the BHD QKD system security under the potential individual intercept-resend attack and the intermediate-base attack.
This paper presents the principles and experimental results of an optical fiber QKD system operating at 1550 nm, and using the BB84 protocol with QPSK signals. Our experimental setup consists of a time-multiplexed super-homodyne configuration using P.I.N detectors in a differential scheme as an alternative to avalanche photon counting. Transmission over 11km of optical fiber has been done using this detection scheme and major relevant characteristics such as noise, quantum efficiency and bit error rate (BER) are reported.
Abstract We propose a quantum key distribution system using balanced homodyne detection, in which strong reference pulses are time‐multiplexed with weak signal pulses by means of fiber interferometer. We use a dual‐threshold decision scheme for postdetection to improve the system performance in terms of BER, with a trade‐off in effective key generation rate. We conduct experimental measurements at 64 km SMF fiber at 1550 nm wavelength, and we prove that the system security can also be enhanced with properly selected threshold parameters. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1934–1939, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24471
Optical homodyne detection is widely adopted in continuous-variable quantum key distribution for high-rate field measurement quadratures. Besides that, those detection schemes have been being implemented for single-photon statistics characterization in the field of quantum tomography. In this work, we propose a discrete-variable quantum key distribution (DV-QKD) implementation that combines the use of phase modulators for high-speed state of polarization (SOP) generation, with a conjugate homodyne detection scheme which enables the deployment of high speed QKD systems. The channel discretization relies on the application of a detection threshold that allows to map the measured voltages as a click or no-click. Our scheme relies also on the use of a time-multiplexed pilot tone-quantum signal architecture which enables the use of a Bob locally generated local oscillator and opens the door to an effective polarization drift compensation scheme. Besides that, our results shows that for higher detection threshold values we obtain a very low quantum bit error rate (QBER) on the sifted key. Nevertheless, due to huge number of discarded qubits the obtained secure key length abruptly decreases. From our results, we observe that optimizing the detection threshold and considering a system operating at 500 MHz symbol generation clock, a secure key rate of approximately 46.9 Mbps, with a sifted QBER of [Formula: see text] over 40 km of optical fiber. This considering the error correction and privacy amplification steps necessary to obtain a final secure key.