Abstract:Side channel effects such as temporal disparity and intensity fluctuation of photon pulses caused by random bit generation with multiple laser diodes in high-speed polarization-based BB84 quantum key distribution (QKD) systems can be eliminated by increasing DC bias current condition. However, background photons caused by the spontaneous emission process under high DC bias current degrade the performance of the QKD systems. In this study, we investigated, for the first time, the effects of spontaneously emitte… Show more
“…Most of our quantum signals were detected within a time window of 1.75 ns. In our experiments, atmospheric turbulences played no role in FHWM broadening effects because quantum signals were transmitted over the short distance of 275 m. Note that slight detection events spread in all temporal regions were caused by spontaneously emitted photons because of a non-negligible DC bias level to the laser diodes, which is an important requirement to eliminate recently reported critical side channel effects of random bit generation with multiple laser diodes 11 , 12 . Figure 2 Probability distribution of the detection events of the SPD for QKD operation at a clock rate of 100 MHz at night.…”
One of the challenges of implementing free-space quantum key distribution (QKD) systems working in daylight is to remove unwanted background noise photons from sunlight. Elaborate elimination of background photons in the spectral, temporal, and spatial domains is an indispensable requirement to decrease the quantum bit error rate (QBER), which guarantees the security of the systems. However, quantitative effects of different filtering techniques and performance optimization in terms of the secure key rate have not been investigated. In this study, we quantitatively analyze how the performance of the QBER and the key rates changes for different combinations of filtering techniques in a free-space BB84 QKD system in daylight. Moreover, we optimize the conditions of filtering techniques in order to obtain the maximum secure key rate.
“…Most of our quantum signals were detected within a time window of 1.75 ns. In our experiments, atmospheric turbulences played no role in FHWM broadening effects because quantum signals were transmitted over the short distance of 275 m. Note that slight detection events spread in all temporal regions were caused by spontaneously emitted photons because of a non-negligible DC bias level to the laser diodes, which is an important requirement to eliminate recently reported critical side channel effects of random bit generation with multiple laser diodes 11 , 12 . Figure 2 Probability distribution of the detection events of the SPD for QKD operation at a clock rate of 100 MHz at night.…”
One of the challenges of implementing free-space quantum key distribution (QKD) systems working in daylight is to remove unwanted background noise photons from sunlight. Elaborate elimination of background photons in the spectral, temporal, and spatial domains is an indispensable requirement to decrease the quantum bit error rate (QBER), which guarantees the security of the systems. However, quantitative effects of different filtering techniques and performance optimization in terms of the secure key rate have not been investigated. In this study, we quantitatively analyze how the performance of the QBER and the key rates changes for different combinations of filtering techniques in a free-space BB84 QKD system in daylight. Moreover, we optimize the conditions of filtering techniques in order to obtain the maximum secure key rate.
“…It should be noted that if the multi-laser scheme is adopted, the parameters of photons from different lasers, such as the wavelength, repetition frequency, pulse width, PER, etc., should be kept indistinguishable to eliminate the risk of the sidechannel loopholes [84,85] . Therefore, the scheme with a single laser is a better solution from the viewpoint of practical security.…”
Section: Generating and Manipulating High-quality Quantum Optical Signalsmentioning
“…In addition, existent standard Quantum Key Distribution (QKD) setups can be adapted to implement OKD, since both protocols share the same requirements for the generation and measurement of photons. Notably, QKD setups have already demonstrated secret key rates of the order of 10 6 bits per second [44][45][46][47][48]. It is also worth mentioning that, as opposed to QKD, OKD is useful even in the case when Alice and Bob are at the same location.…”
The oblivious transfer primitive is sufficient to implement secure multiparty computation. However, secure multiparty computation based on public-key cryptography is limited by the security and efficiency of the oblivious transfer implementation. We present a method to generate and distribute oblivious keys by exchanging qubits and by performing commitments using classical hash functions. With the presented hybrid approach of quantum and classical, we obtain a practical and high-speed oblivious transfer protocol. We analyse the security and efficiency features of the technique and conclude that it presents advantages in both areas when compared to public-key based techniques.
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