  Based on the intrinsic random property of quantum mechanics, quantum random
number generators allow for access of truly unpredictable random sequence and
are now heading towards high performance and small miniaturization, among which
a popular scheme is based on the laser phase noise. However, this scheme is
generally limited in speed and implementation complexity, especially for chip
integration. In this work, a general physical model based on wiener process for
such schemes is introduced, which provides an approach to clearly explain the
limitation on the generation rate and comprehensively optimize the system
performance. We present an insight to exploit the potential bandwidth of the
quantum entropy source that contains plentiful quantum randomness with a simple
spectral filtering method and experimentally boost the bandwidth of the
corresponding quantum entropy source to 20 GHz, based on which an ultra-fast
generation rate of 218 Gbps is demonstrated, setting a new record for laser
phase noise based schemes by one order of magnitude. Our proposal significantly
enhances the ceiling speed of such schemes without requiring extra complex
hardware, thus effectively benefits the corresponding chip integration with
high performance and low implementation cost, which paves the way for its
large-scale applications.

Quantum Physics