Quantum key distribution system clocked at 2 GHz

School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, Scotland, United Kingdom
Optics Express (Impact Factor: 3.49). 05/2005; 13(8):3015-20. DOI: 10.1364/OPEX.13.003015
Source: arXiv


An improved quantum key distribution test system operating at clock rates of up to 2GHz using a specially adapted commercially-available silicon single-photon counting module is presented. The use of an enhanced detector has improved the fiber-based quantum key distribution test system performance in terms of transmission distance and quantum bit error rate.

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    • "Silicon (Si) based avalanche photodiodes (APDs) have been the preferred technology in detecting light with visible wavelengths due to the low cost and low excess avalanche noise. Si APD, which enhances the overall signal to noise ratio of a receiver module, has been employed to achieve high energy resolution and fast time response in X-ray detection [1] [2] and used as single photon avalanche diodes (SPADs) in applications such as positron emission tomography systems [3], quantum key distribution (QKD) [4] [5], photon counting time-of-flight sensor [6], non-invasive testing of VLSI circuits [7] and photon correlation spectroscopy [8]. Detailed understanding of impact ionization process is essential for designing and modelling of high performance APDs, SPADs and Si based power devices. "
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    ABSTRACT: A Simple Monte Carlo model has been developed to model the avalanche characteristics of Silicon. Good agreement with experimental results from Silicon p+-i-n+ diodes with i-regions ranging from 0.082 to 0.26 μm, an n+-i-p+ diode with an i-region of 0.82 μm and a p+n diode was obtained. Therefore our model can be used to model the avalanche process in diodes with varying electric field profiles. We also studied the competing effects of the ratio of electron to hole ionization coefficients and the dead space on excess noise factor, by varying these parameters in our simulations of ideal p+-i-n+ diodes with avalanche regions width of 0.05 to 0.3 μm to cover the electric field range in the measured devices. As avalanche region width reduces from 0.3 to 0.05 μm, the electron to hole ionisation coefficient ratio decreases from 3.42 to 1.23 while the dead space to avalanche width ratio increases from 0.19 to 0.49 for electrons. The former increases the excess noise while the latter suppresses the avalanche noise such that on balance, a weak dependence of excess noise on the avalanche width for w < 0.3 μm was observed in these p+-i-n+ diodes, consistent with the excess noise results reported in thin Silicon p+-i-n+ diodes.
    Full-text · Article · Aug 2012 · Journal of Instrumentation
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    • "Nowadays, a new demand for high count rate emerges from different fields (e.g. spectroscopy, free space and fiber based quantum cryptography [4] [5] [6] [7] [8], fast Quantum Random Number Generators [9] [10], reflectometry [11] [12] or astronomy [13] [14]). A solution has been found with NbN superconducting single photon detectors [15], demonstrating GHz-count rates. "
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    ABSTRACT: We demonstrate fast counting and multiphoton detection abilities of a Silicon Photo Multiplier (SiPM). In fast counting mode we are able to detect two consecutive photons separated by only 2.3 ns corresponding to 430 MHz. The counting efficiency for small optical intensities at lambda= 532 nm was found to be around 16% with a dark count rate of 52 kHz at T= -5 masculine C. Using the SiPM in multiphoton detection mode, we find a good signal discrimination for different numbers of simultaneously detected photons.
    Full-text · Article · Nov 2007 · Optics Express
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    • "For most QKD links the loss and dead time are such that detector timing resolution plays a dominant role in determining the optimum transmission rate [1] [2] [3] [5]. However, as the disparity between detector timing resolution and recovery time grows with improved timing resolution, transmission-rate limitations imposed by dead-time effects will become more significant. "
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    ABSTRACT: Recent advances in quantum key distribution (QKD) have given rise to systems that operate at transmission periods significantly shorter than the dead times of their component single-photon detectors. As systems continue to increase in transmission rate, security concerns associated with detector dead times can limit the production rate of sifted bits. We present a model of high-speed QKD in this limit that identifies an optimum transmission rate for a system with given link loss and detector response characteristics.
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