Synchronization of free-space quantum key distribution

Wu, Qinglin; Han, Zheng‐Fu; Miao, Er-Long; Liu, Yun; Dai, Yuan; Guo, Guang-Can

doi:10.1016/j.optcom.2007.03.068

Cited by 12 publications

(6 citation statements)

References 9 publications

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“…In quantum cryptography, for example, fiber-based (working at 1550 nm) and free space (typically at 1064 nm) QKD systems need high-count-rate detectors to guarantee high secret-bit rates [1]. The ideal detector should also work in free-running mode in order to avoid issues related to the synchronization between the transmitter and the receiver, which can lead to strong reduction of the system detection efficiency [2], and to prevent its vulnerability to illumination attacks [3]. Other applications could also benefit from non-gated detectors, like LIDAR with gigahertz clock rates [4] and singlet oxygen detection, where long time constants need to be reconstructed [5].…”

Section: Introductionmentioning

confidence: 99%

Gate-Free InGaAs/InP Single-Photon Detector Working at Up to 100 Mcount/s

et al. 2013

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Recently, there has been considerable effort to develop photon-counting detectors for the near-infrared wavelength range, but the main limitation is to have a practical detector with both high count rates and low noise. Here, we show a novel technique to operate InGaAs/InP single-photon avalanche diodes (SPADs) in a free-running equivalent mode at high count rate up to 100 Mcount/s. The photodetector is enabled with a 915-MHz sinusoidal gate signal that is kept unlocked with respect to the light stimulus, resulting in a free-running equivalent operation of the SPAD, with an afterpulsing probability below 0.3%, a photon detection efficiency value of 3% at 1550 nm, a temporal resolution of 150 ps, and a dark count rate below 2000 count/s. Such gate-free approach can be used to measure, at high count rate, signals in continuous wave or with slow time decays, where standard gated detectors would not be suitable

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Section: Introductionmentioning

confidence: 99%

Gate-Free InGaAs/InP Single-Photon Detector Working at Up to 100 Mcount/s

et al. 2013

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“…As a result, the detector does not always trigger exactly on the rising edge of a synchro pulse and has some non-zero probability of being triggered during some time behind it. Indeed, it was shown that intensity fluctuations of synchronization light can lead to a significant synchronization error under certain conditions [24]. A detailed study of this phenomenon is beyond the scope of this work and it can be a topic of a separate research.…”

Section: The Obtained Resultsmentioning

confidence: 91%

“…As one can see, the 2nd term in (24) is ~1 𝑁 and it therefore tends to 0 at 𝑁 → ∞. At the same time, the 1st term does not depend on 𝑁.…”

Section: Synchronization Precision Minimum Nmentioning

confidence: 86%

A fast and efficient algorithm for time synchronization in satellite quantum key distribution

Miller

2024

J. Phys.: Conf. Ser.

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Time synchronization is one of the most crucial issues that must be addressed in developing quantum key distribution (QKD) systems. It not only lets the transmitter and the receiver to assign a sequence number to each event and then do correct basis reconciliation, but also allows to increase signal-to-noise ratio. Time synchronization in satellite communications is especially complicated due to such factors as high loss, signal fading and Doppler effect. In this work, a simple, efficient and robust algorithm for time synchronization is proposed. It was tested during experiments on QKD between Micius, the world’s first quantum communications satellite, and an optical ground station located in Russia. The obtained synchronization precision lies in the range from 467 to 497 ps. The authors compare their algorithm for time synchronization with the previously used methods. The proposed approach can also be applied to terrestrial QKD systems.

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“…Then Bob records the TOAs of all the output signals of the SPDs using the time-to-digital convertor (TDC) and saves the TDC data to a local memory. [9,10] Therefore, the TOA accuracy reflects the system timing precision, which is affected by the time synchronization imperfection [11,12] and the system jitters caused by the single photons source, [13] de-tection device, [14,15] TDC, [10,16,17] etc. Moreover, these factors bring an inevitable result that the temporal distribution of the single-photon pulse is expanded.…”

Section: Introductionmentioning

confidence: 99%

Performance optimization for quantum key distribution in lossy channel using entangled photons

Yu¹,

Xu²,

Zhang

et al. 2017

Chinese Phys. B

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In quantum key distribution (QKD), the times of arrival of single photons are important for the keys extraction and time synchronization. The time-of-arrival (TOA) accuracy can affect the quantum bit error rate (QBER) and the final key rate. To achieve a higher accuracy and a better QKD performance, different from designing more complicated hardware circuits, we present a scheme that uses the mean TOA of M frequency-entangled photons to replace the TOA of a single photon. Moreover, to address the problem that the entanglement property is usually sensitive to the photon loss in practice, we further propose two schemes, which adopt partially entangled photons and grouping-entangled photons, respectively. In addition, we compare the effects of these three alternative schemes on the QKD performance and discuss the selection strategy for the optimal scheme in detail. The simulation results show that the proposed schemes can improve the QKD performance compared to the conventional single-photon scheme obviously, which demonstrate the effectiveness of the proposed schemes.

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Synchronization of free-space quantum key distribution

Cited by 12 publications

References 9 publications

Gate-Free InGaAs/InP Single-Photon Detector Working at Up to 100 Mcount/s

Gate-Free InGaAs/InP Single-Photon Detector Working at Up to 100 Mcount/s

A fast and efficient algorithm for time synchronization in satellite quantum key distribution

Performance optimization for quantum key distribution in lossy channel using entangled photons

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