(Phys.org) The research team led by academician GUO Guangcan from the University of Science and Technology of China of the Chinese Academy of Sciences has made security analysis and improvement of source independent quantum random number generators with imperfect devices.
By studying the actual characteristics of the measurement devices of the source-independent quantum random number generation, the researchers pointed out that the security issues were caused by afterpulse, detection efficiency mismatching, poor sensitivity to photon number distribution in measurement devices, etc., and gave the corresponding solutions.
To solve the problem of detection efficiency mismatch and poor detector sensitivity to the distribution of light source, the researchers proposed a method for monitoring the distribution of light source, and gave a bit rate formula based on the composable security with full consideration to the finite length effect.
This study has quantitatively analyzed the security problem caused by imperfect measurement devices in source-independent quantum random number systems and given the corresponding solutions, which provides an important theoretical support for the realization of ultra-fast commercial source-independent quantum random number generator.

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