  Random numbers are an essential resource to many applications, including
cryptography and Monte Carlo simulations. Quantum random number generators
(QRNGs) represent the ultimate source of randomness, as the numbers are
obtained by sampling a physical quantum process that is intrinsically
probabilistic. However, they are yet to be widely employed to replace
deterministic pseudo random number generators (PRNG) for practical
applications. QRNGs are regarded as interesting devices. However they are
slower than PRNGs for simulations and are typically seen as clumsy laboratory
prototypes, prone to failures and unreliable for cryptographic applications.
Here we overcome these limitations and demonstrate a compact and self-contained
QRNG capable of generating random numbers at a pace of 8 Gbit/s uninterruptedly
for 71 days. During this period, the physical parameters of the quantum process
were monitored in real time by self-checking functions implemented in the
generator itself. At the same time, the output random numbers were analyzed
with the most stringent suites of statistical tests. The analysis shows that
the QRNG under test sustained the continuous operation without physical
instabilities or hardware failures. At the same time, the output random numbers
were analyzed with the most stringent suites of statistical tests, which were
passed during the whole operation time. This extensive trial demonstrates the
reliability of a robustly designed QRNG and paves the way to its use in
practical applications based on randomness.
